Use it in your work · Beginner

Choosing and Using the Tools

Draft, open for academic review

A comparison written by someone selling none of them.

Your progress here is recorded once you pass the AI at Work exam.

8 modules. 76 lessons.

What a tool is made of

9 lessons · 1 h 15

You will be able toTake any AI product you are handed, name the exact model and size class inside it, say whether its thinking mode, context handling, system prompt or tool layer is producing the behaviour you are seeing, and predict which of those will change without notice.

  1. 1.1What you are actually choosingStart7 min
  2. 1.2Reading a model’s name9 min
  3. 1.3Small, medium, large: what the size label buys9 min
  4. 1.4Thinking modes, and what you pay for them8 min
  5. 1.5The context window is a ceiling, not a promise9 min
  6. 1.6The instructions you never see8 min
  7. 1.7What ‘it can browse the web’ actually means9 min
  8. 1.8‘It understands images’: what that buys8 min
  9. 1.9When the engine gets swapped8 min
An illustrative case, built from documented patternsThe Tuesday the sorting brokeA scholarship trust in Nagpur, eleven days before its application deadline, with a sorting tool that has quietly stopped agreeing with itself

Sahyog Vidya Trust awards forty scholarships a year and receives about nine hundred applications for them. Each arrives as an email with a short statement of circumstances. A volunteer, Deepak, a second-year engineering student, built a sorter for it last March: paste the statement, and a free chat assistant returns one of six categories: first-generation learner, single-earner household, disability in the family, migrant household, girl child in a low-enrolment block, or none of these. The category decides which reviewer reads it and, for two of the six, which pot of money it is considered against.

It ran for seven months. Once a fortnight a trustee, Mrs Fernandes, read a sample of forty sorted applications against the trust’s own written rules, and agreement had sat between ninety and ninety-five per cent all year. Nobody had touched the prompt since May.

On a Tuesday in March her sample came back at sixty-eight per cent. The errors were not scattered. Applications mentioning a father who had died were landing in single-earner household, when the trust’s rules put a bereaved family into a separate review with a different reviewer and a different maximum award.

Shobha, who runs the programme, wanted to move to a different product that morning. Eleven days remained before the deadline and four hundred applications were still to arrive. Her argument was that the sample was the only quality check the trust had, that it had failed, and that spending the day investigating a free tool was a day the applications did not stop coming.

Deepak’s argument was that he did not know what had changed, and that a different product would be a different unknown. He had not edited the prompt. The trust was on a free account whose model picker had said Auto since the day he created it (a routing label, not a model name) and he had never looked at it in seven months. He could name three things that might have moved and had evidence for none of them.

The first was the model. Free tiers move you to a smaller model once an allowance is used, and the trust’s sorting runs in bursts, so the afternoon batch might be answered by something different from the morning batch. The second was the product’s own instructions, which the company rewrites without telling anyone. The third was the applications themselves. A new district scheme had opened in Gadchiroli in February, and those statements read differently: longer, and frequently describing two hardships at once.

Deepak’s prompt held six rules in a single paragraph.

Shobha’s counter was fair. Whatever had moved, the trust still had to sort four hundred applications correctly, and diagnosis is not sorting. She offered him until four o’clock, and pointed out that she could put two volunteers on manual sorting for the rest of the week, which would cost the trust about nine hours of work it had not budgeted for and would at least be work whose failures somebody could see.

Deepak’s objection to that was that manual sorting had its own error rate and nobody had ever measured it. The ninety-three per cent figure was agreement between the tool and Mrs Fernandes, not between the tool and the truth. He did not know how often two volunteers would agree with each other on the same forty applications, and neither did she.

Mrs Fernandes, when asked, made the point that decided the afternoon. She had been sampling for seven months and she had nothing written down except a tally. She could not say whether the tool had ever been good at bereavement cases, because bereavement cases are perhaps one application in twenty and her samples were forty at a time. It was entirely possible that the category had always been wrong and March was simply the month a sample had caught it.

That changed the shape of the problem. If the fault was seven months old, then a hundred and some applications had been misrouted since September, several of them to a smaller pot of money, and that was a separate matter from the deadline.

The thing all three agreed on was that the question was not which tool to use. It was which of the three layers had moved, or whether anything had moved at all, because the answer determined whether the fix was an hour or a fortnight, and because the trust had nothing written down that could tell them.

What would you have done with the afternoon, and what would you have wanted to exist before that Tuesday?

How it played out

It took four hours. Deepak built the check he should have had already: sixty applications from January, with Mrs Fernandes’s own labels beside them, in a plain text file. He ran those sixty through the tool again. Fifty-seven came back correct: the same as in January. So the tool had not become worse at January’s material.

Then he ran sixty from the previous week. Forty-one correct. The inputs had changed, not the tool. The Gadchiroli statements were longer and mentioned more than one hardship, and a prompt with six rules in a paragraph was being followed to about five of them, with the middle ones dropped. Nothing had been deployed by anybody.

The fix took forty minutes: the six rules became a numbered list, and a seventh was added stating explicitly that a deceased parent goes to bereavement review even when the household now has one earner. Both sets then scored above ninety per cent. They kept the sixty labelled applications as a permanent file and ran them whenever anything felt wrong. In August the tool genuinely did change (the answers became longer and started arriving with headings) and they knew within fifteen minutes that this time it was not them.

Worth arguing about

  1. Deepak’s first thought was that the model had got worse, and Shobha’s was to change product. Why was neither the right first move?

    One answer

    Both skip the question that decides what the fix costs. A chat product is a model, a product layer of unseen instructions, and a route, and the input is a fourth thing that can change on its own. A model swap, a rewritten system prompt, a router serving something smaller after the free allowance runs out, and a new kind of application all produce the same symptom. Changing product without knowing which one moved carries the risk of reproducing the fault on the new tool, and blaming the model leaves a prompt fault unfixed.

  2. Why did sixty labelled applications from January settle the question so quickly?

    One answer

    Because they were fixed material with known correct answers. Running them again holds the input constant, so a drop in score can only come from the tool. Holding the score means the tool is unchanged and something else moved. Without that file the trust had only Deepak’s memory of the tool having been fine, and memory of software quality is unreliable in one direction: the early good answers are remembered and the early failures are not, so everything feels as though it has declined.

  3. A free chat account cannot pin a model version. What did the trust do instead, and what does that not protect against?

    One answer

    It kept a dated file of labelled examples and re-ran them whenever behaviour seemed off. That detects a change, quickly and cheaply. It does not prevent one: on a consumer plan there is no version to pin, no changelog granular enough and no undo, so the trust can be moved onto a different model mid-deadline and find out only afterwards. Detection is what a free tier permits; prevention requires a pinned snapshot on an API.

Test yourself6 questions on this modulePractice. Nothing is recorded and no score is kept.
  1. 1

    You upload the same forty-page contract to two services that both state they run the identical open model and version. One returns a clause-by-clause summary; the other misses half the document. What is the most likely explanation?

  2. 2

    You run an unattended script that classifies support tickets. Why does calling the alias rather than the dated snapshot change the risk you carry?

  3. 3

    A small model is given a prompt containing seven rules and reliably follows five of them. What does the ladder in this module say to do first?

  4. 4

    You switch thinking mode on for a question about the current registration fee for a certificate in your state. What should you expect?

  5. 5

    Why does putting your question after a long document, rather than before it, measurably improve recall?

  6. 6

    An answer that used web search turns out to be wrong. What should you check first?

Testing a tool yourself

10 lessons · 1 h 20

You will be able toBuild a personal benchmark of a dozen real tasks with written success criteria, run a blind scored comparison across three candidates while accounting for run-to-run variation, and record a decision that names the exact model versions and the conditions that would reverse it.

  1. 2.1Where they differ, and where it is marketing8 min
  2. 2.2The file you will keep for years9 min
  3. 2.3The prompts where you already know the answer8 min
  4. 2.4Testing the language you actually work in9 min
  5. 2.5Taking the brand off the answers7 min
  6. 2.6Run it five times8 min
  7. 2.7A rubric you can apply in ten seconds7 min
  8. 2.8Reading a leaderboard without being fooled9 min
  9. 2.9Testing the edges: refusals and house manners8 min
  10. 2.10Making the decision, and recording it7 min
An illustrative case, built from documented patternsTwelve prompts against a leaderboardA two-person legal practice in Aurangabad choosing an assistant for drafting in Marathi and English, with an annual discount expiring on Friday

Advocate Anjali Kulkarni takes consumer disputes, tenancy matters and small commercial work. Her associate, Rehan, is eighteen months qualified. Most of the drafting is in English; the client letters and the statutory notices are in Marathi, and the register of a legal notice in Marathi is not something either of them will accept an approximation of.

One of the two products they were considering had an annual plan at eighteen per cent off, and the offer ended on Friday. That is what made this a decision rather than a discussion.

Anjali had read a comparison that gave Tool B a four-point lead over Tool A on a reasoning benchmark and two points on a coding one. She had also used Tool A on and off for eight months and liked it. Rehan pointed out two things about the comparison. Neither of them writes code. And neither benchmark contained a single item in Marathi, which is the part of the work where a bad answer is unusable rather than merely irritating.

His proposal was a blind test: twelve real prompts from their own files, run through three candidates in one sitting, answers labelled A, B and C, scored against criteria written before any answers were read, and the mapping turned face down until the end. He wanted Thursday afternoon for it.

Thursday had two hearings. That was the cost on Rehan’s side, and it was not small in a two-person practice in a week with a filing deadline.

The cost on Anjali’s side was less visible and larger. An annual commitment in a field where the right tool changes within six months converts a reversible choice into an irreversible one, and the saving was about fourteen hundred rupees: less than an hour of her time. And a choice made on a benchmark that contained none of her work would be re-litigated every time somebody published another one.

There was a third problem that Rehan raised and Anjali initially dismissed. Her eight months of favourable impressions of Tool A came from an account that had been told, across hundreds of conversations, that she practises tenancy law in Maharashtra. A tool that has learned your domain looks better on your domain. Comparing that account against two fresh ones is not a comparison of tools.

They argued about the number of prompts. Anjali thought six was enough and that she would know which tool was which regardless of the labels. Rehan’s answer was that knowing which is which is exactly the thing the labels are for, and that if she could genuinely identify them, the blinding costs nothing and the score is still the score.

One prompt in the twelve was of a kind Anjali had never used deliberately: a question about a provision of consumer protection law whose answer she already knew, written out in advance, with the section number and the source and the date she last checked it. Rehan had wanted two of these. Anjali thought one was enough, on the reasonable ground that they were buying a drafting tool and not an encyclopaedia.

His reply was the argument that changed her mind about the shape of the test. They were not buying a drafting tool. They were buying something a junior would use on a Friday evening when nobody senior was in the office, and the failure that costs a practice money is not a clumsy sentence. It is a confident paragraph containing a provision that does not exist, in a letter that goes out over her name.

There was one more thing to settle before Wednesday, and it was the part they nearly got wrong. Rehan proposed scoring each answer out of two: usable as it stands, usable after a fix, or rewrite from scratch. Anjali asked what they were scoring against. Neither of them had written down what a good answer to the Marathi notice contained.

They spent twenty minutes on that before they ran anything: one line per prompt saying what a good answer would have in it. For the notice it was four things: correct statutory register, the demand stated once and plainly, a date for compliance, and no English word order dressed in Marathi. Written afterwards, those criteria would have rearranged themselves around whichever answer impressed them first.

What would you have run, and with the discount expiring, when would you have run it?

How it played out

They ran nine prompts, not twelve, on Wednesday evening rather than Thursday afternoon: three hours, fresh private windows for all three tools, memory and custom instructions off, the same pasted context for each.

Blind scores were fifteen, fourteen and nine out of eighteen. Two tools were effectively equivalent and one was not. The surprise was that the tool Anjali expected to lead was one of the two near-equals rather than ahead of the other, and that the gap between them came almost entirely from one prompt: the Marathi statutory notice, where one produced grammatically correct Marathi in the register of a translated English letter.

The known-answer prompt decided it. Both leading tools gave a section number. One was right. The other was confidently wrong and supplied a case name in perfect citation format that did not exist. Then Rehan typed three words: are you sure? — and the tool that had been right abandoned its correct answer and agreed with him.

They chose the other one. They did not take the annual plan; they paid monthly and put a review in the calendar for September. The eighteen per cent was the price of being able to change their minds in a field where they expected to.

Worth arguing about

  1. Anjali’s account had eight months of tenancy context in it. Why did that make her impression useless as a comparison?

    One answer

    Because she was not comparing three tools, she was comparing one differently configured version of her own history against two strangers. Memory, custom instructions and past conversations make a tool look better on the domain it has been told about. A fair run needs a fresh or private window for each candidate, memory and custom instructions off, and the same context pasted into all three, which costs a few minutes and removes the largest confound in any home-made comparison.

  2. The known-answer prompt scored three things. Which one decided the choice, and why is it more useful than raw accuracy?

    One answer

    Whether the tool held its answer under pressure. Two prompts cannot estimate an error rate: a tool that gets both right may still be wrong often on material nobody tested. But whether a tool hedges when uncertain, and whether it abandons a correct answer because the user sounded doubtful, are stable properties across topics in a way accuracy on a small sample is not. A model that folds when questioned is dangerous for anyone who is not already the expert, and that is precisely the situation the tool is being bought for.

  3. They gave up an eighteen per cent discount. What did they buy with it?

    One answer

    The ability to act on their own September review. An annual plan in a field where the right tool changes within six months converts a reversible decision into an irreversible one for the sake of a few hundred rupees a month, and having paid for a year people defend the choice and stop noticing when the condition they wrote down has been met. The discount is real money; so is being stuck with the loser of a test you have not run yet.

Test yourself6 questions on this modulePractice. Nothing is recorded and no score is kept.
  1. 1

    Why does the prompt file ask you to write down what a good answer contains before you see any answers?

  2. 2

    A candidate tool fails one of your twelve prompts on the first attempt. What does that single result establish?

  3. 3

    You run twelve prompts through three tools while signed into accounts you have used for months. What have you actually measured?

  4. 4

    On a benchmark where the leading models all score above ninety per cent, why are the remaining gaps largely uninformative?

  5. 5

    A nurse finds one product refuses a drug-interaction question while another, running the same model, answers with a caveat. Where does that difference usually live?

  6. 6

    Which part of a written decision record does most to stop you re-litigating the choice whenever a new benchmark appears?

The routes in

9 lessons · 1 h 15

You will be able toChoose the right route to a model for a given job (web, phone, desktop, API, free front-end, router, editor or terminal) set one up with a hard spend cap and a revocable key, and judge an extension or wrapper by its permissions, publisher and disclosed data use before installing it.

  1. 3.1The web app, the phone app and the desktop app8 min
  2. 3.2Your first API call9 min
  3. 3.3Keys, spend caps, and the bill nobody wants8 min
  4. 3.4Building your own chat app for nothing8 min
  5. 3.5Routers: one key, many models8 min
  6. 3.6Where a coding assistant lives9 min
  7. 3.7Extensions, wrappers and the permission dialog8 min
  8. 3.8When the phone is the computer9 min
  9. 3.9Voice, screen readers and hands-free use8 min
An illustrative case, built from documented patternsForty machines and one keyA polytechnic in Coimbatore deciding how a hundred and eighty second-year students will reach an assistant for a semester project

The department of computer applications has forty lab machines with eight gigabytes of memory each, a shared Windows image, and students in three batches. Nearly all the students also have phones: mid-range Android, storage close to full, data bought in bundles. The head of department, Mr Selvaraj, had forty-five thousand rupees for the semester and a project brief that required every student to use an assistant and to record what it cost them.

Four routes were put on the table at a staff meeting and the arithmetic disposed of one immediately. A hundred and eighty personal subscriptions at twenty dollars a month is not a semester budget, it is a department’s annual one.

The second was a single department key on an open-source front-end installed on the lab server, with every student reaching it from a browser. One account to set up, one bill, works on the lab machines and from the students’ phones on the college network. Mr Selvaraj wanted this and wanted it on Monday.

Vimala, the lab technician, objected on two grounds, and her objections were the substance of the meeting. A single shared key means there is no way to tell whose request cost what, so a runaway spend is a mystery as well as a bill. And a student loop with a retry on failure, running against two thousand items on a Thursday night, can empty the semester’s budget before anybody sees an email.

Her alternative was a router with a separate key per student and a spending limit on each. That answers both objections exactly. It also means creating and later revoking a hundred and eighty keys, in a semester where she was already running three other labs, and it means somebody handling the prepaid balance every few weeks.

The fourth route was to tell students to use free tiers on their own devices, which costs nothing and produces no comparable work, because the tools cap at different points, some of the apps are not listed for older Android versions, and several students did not have three hundred megabytes free to install anything.

Then a student asked whether he could simply install a browser extension that put an assistant beside every page. The department had no policy. The extension’s permission line said it could read and change all data on all websites, and the lab machines are used to log into the college’s internal portal, where attendance and marks live.

Vimala had a second objection to the shared key that nobody expected, and it was the better one. The project brief required each student to record what their work had cost. With one key and no attribution, the only number available is the department’s total, which teaches nothing. The students would be writing down a figure somebody else had calculated for them, which is the opposite of the exercise.

A lecturer, Mrs Anitha, raised the case nobody had planned for. Eleven of the hundred and eighty students are in the evening batch and come to the lab twice a week. Whatever route the department chose had to work from a phone on a metered connection at home, or those eleven would do the project by borrowing somebody’s laptop on a Saturday.

That put a constraint on the answer that the budget had not. Voice and image uploads are expensive on a bundle; text is not. A photograph is a megabyte or more and a whole afternoon of text conversation is a few. Whatever was chosen had to be usable as text on a poor connection, and anything that streamed long replies over a connection that dropped would lose the answer along with the data spent on it.

Mr Selvaraj’s position was that Monday mattered: a route that exists imperfectly on Monday teaches more than a perfect one that arrives in week four. Vimala’s position was that the first runaway loop would end the experiment for everybody, and that the person who would be asked to explain it to the principal was her.

What would you have run, and what would you have spent the budget’s first rupee on?

How it played out

They took the shared key and closed Vimala’s objections a different way. The front-end supports its own user accounts, so each student signed in individually while a single key sat behind all of them. That gave attribution (whose conversation, how many tokens) without a hundred and eighty keys to create and revoke.

The key’s cap was set in the provider’s console at four thousand rupees for the month, under a tenth of the budget, with a written rule that it would not be raised mid-month. Two alert thresholds were set on the same page.

The front-end’s history setting, which by default resends the whole conversation on every message, was capped at the last ten. Spend in the second week was less than half the first week’s for the same number of students, and nobody noticed a difference in the answers.

On the phones, the assistants were installed from the browser to the home screen rather than from the app store, which cost a few hundred kilobytes instead of three hundred megabytes and sidestepped the two students whose Android version was not supported.

Extensions were prohibited on lab machines, and the permission line was read aloud in the class that asked, which did more than the prohibition. In week six a retry loop did run away against two thousand items. It stopped at four thousand rupees on a Thursday night, and the log named the account in under a minute.

Worth arguing about

  1. A shared key with per-user accounts in the front-end is not the same as per-user keys. What does it give you, and what does it not?

    One answer

    It gives attribution: the front-end records which account sent which conversation and how many tokens it used, so a spike has a name against it. It does not give isolation. There is still one credential, so a leak revokes access for everyone rather than for one person, one student cannot be cut off without changing the key, and the spending limit is shared: the cap protects the department’s budget but not one student’s share of it from being consumed by another’s loop.

  2. Capping the history at the last ten messages halved the spend in a week. Why is that the highest-value setting in any of these front-ends?

    One answer

    Because every turn of a conversation resends everything before it, so the twentieth message of a long chat costs many times the first. Most of the money in conversational use is earlier turns being re-read, not new text being written. Capping the resent history removes that cost with almost no effect on quality for ordinary work, and it is switched off by default in every one of these applications.

  3. Why did the department explain the extension’s permission rather than simply prohibiting extensions?

    One answer

    Because the prohibition only covers the lab. Students will install extensions on their own machines, and a rule they do not understand does not travel with them. The permission line (read and change all your data on all websites) is what makes the risk concrete: an extension with it can read every page the user is logged into, including a bank dashboard or the college portal, and extensions are sold and updated after installation. Teaching the check (publisher, age, recent reviews, data disclosure) is the part that is still useful after the semester.

Test yourself6 questions on this modulePractice. Nothing is recorded and no score is kept.
  1. 1

    Why is the same subscription usually more expensive bought inside a phone app than on the company’s website?

  2. 2

    An API answer stops in the middle of a word. What is the usual cause?

  3. 3

    You committed a file containing an API key, then added it to the ignore list and deleted the file in a later commit. What is the state of the key?

  4. 4

    Which single setting in a free chat front-end most reduces the cost of long working conversations?

  5. 5

    You evaluate an open model through a router and get inconsistent results across one morning. What is the most likely cause?

  6. 6

    A browser extension requests permission to read and change all your data on all websites. What does approving it grant?

What it actually costs

10 lessons · 1 h 18

You will be able toEstimate the cost of a job from a measured sample before running it, cut that cost with prefix caching, batching and model routing without lowering quality, choose between a subscription, prepaid credit and pay-as-you-go for your own pattern of use, and set an enforced cap so the worst case is bounded.

  1. 4.1The free tiers, and their traps8 min
  2. 4.2When paying is worth it8 min
  3. 4.3The unit you are billed in8 min
  4. 4.4Costing a job before you run it8 min
  5. 4.5The two discounts almost nobody uses8 min
  6. 4.6Spending money where it matters8 min
  7. 4.7Subscriptions, credits and pay-as-you-go7 min
  8. 4.8The costs that are not on the invoice8 min
  9. 4.9Paying for it from where you live8 min
  10. 4.10A budget that actually holds7 min
An illustrative case, built from documented patternsForty thousand articles and a launch dateA regional newspaper in Kochi pricing the tagging of its own archive four weeks before a new website goes live

The archive is forty-one thousand articles from 1998 onwards, about sixty per cent in Malayalam and the rest in English. The new site needs three things from each: three tags from a fixed list of sixty, a forty-word standfirst, and a flag on anything naming a living person, which routes the article to a legal read before it is republished.

Thomas, the editor, wanted the whole archive run through the strongest model available. His reasoning was not vanity. The archive is the paper’s only asset that a competitor cannot buy, and a bad tag is a piece of the paper’s history that nobody will ever find again.

Fathima, who is the entire technical department, ran twenty real articles first and wrote down what they actually used: about eighteen hundred tokens in and two hundred and forty out. On the frontier model that priced the job at a little under five hundred dollars. On the small model in the same family it was thirty-one. Thomas looked at both numbers and said the difference was worth it.

Then Fathima checked her sample and found she had taken the twenty articles from the top of a list, which sorted by date. Nineteen were from the last two years and four were in Malayalam. The archive is sixty per cent Malayalam, and Malayalam in its own script takes roughly three times as many tokens as the same content in English.

She re-sampled, stratified by language and by length. The average came out at about three thousand four hundred tokens in and four hundred and twenty out, nearly double her first estimate. The frontier model now priced at about six hundred and seventy-six dollars before retries, about nine hundred with the third she adds for them: a little over seventy-five thousand rupees. The small model came to forty-two dollars all in.

So the disagreement got sharper rather than easier. Thomas wanted the expensive run live, where he could watch it and stop it. Fathima wanted a cascade (the small model on everything, the expensive one only on flagged cases) and she wanted the escalation pass sent through the batch route at half price, which meant results arriving within a day rather than immediately and coming back unordered.

The launch was in four weeks. A prompt fault discovered on day three of a batch run is three days.

Thomas made an argument that deserved more respect than Fathima initially gave it. Seventy-five thousand rupees is a fortnight of a junior sub-editor’s salary, and the paper had spent more than that on worse things. If the expensive model meant not having to think about the tagging again, it was cheap. What he objected to was not the saving but the number of moving parts: two models, an escalation rule, a batch window and a confidence word, each of which could be the thing that went wrong on a Thursday.

Fathima’s answer was that she was not proposing to guess which items the small model could handle. She wanted to measure it on a hundred articles, against tags a person had written by hand, and to design the escalation from what that comparison showed rather than from an opinion about model sizes. Without that measurement a cascade is a guess that quietly ships worse work, and she said so.

The chief sub-editor, who would have to write those hundred sets of tags, wanted to know what happened to his afternoon if the answer came back saying the small model was fine. Fathima’s reply was that the hundred tags were not wasted either way: they were the only record the paper would have of what correct looked like, and the same hundred would be the check the next time anybody touched the prompt.

And there was a category neither of them wanted to route by confidence. A missed living-person flag is not a worse tag. It is a legal read that never happened, on an article about to be republished on a public website with the paper’s name on it.

What would you have measured before spending anything, and where would you have refused to let the cheap model decide?

How it played out

Fathima ran a hundred articles through both models and compared them against tags the chief sub-editor wrote by hand. Seventy-one were right on both. Six were wrong on both, which said the prompt or the task was at fault and not the model. Fifteen were right on the large model and wrong on the small one, mostly long analysis pieces and Malayalam articles where a person was referred to by an honorific rather than a name. And eight were right on the small model and wrong on the large one, almost all of them because the large model had chosen a more precise category that was not among the sixty.

The cascade was built from that. The small model ran everything. Anything over twelve hundred words, anything in which the small model set the living-person flag, and anything where it ended its answer with the word UNSURE went to the large model: about twelve per cent of the archive. The living-person category escalated regardless of confidence, because the cost of being wrong there is not a bad tag.

They ran two hundred articles live on the first morning, found the prompt returning four tags instead of three on Malayalam pieces, fixed it, and only then sent the bulk. The escalation pass went through the batch route overnight. The final bill was a hundred and sixty-four dollars, about fourteen thousand rupees.

The legal reader still found eleven articles the flag had missed, all short Malayalam pieces where the person appeared only by title. A free keyword pass over a list of three hundred local titles caught nine of them.

Worth arguing about

  1. Fathima’s first twenty items came from the top of a date-sorted list. What did that do to the estimate, and what is the general rule?

    One answer

    It understated the job by nearly half, because recent articles are shorter and the sample was overwhelmingly English while the archive is mostly Malayalam, which costs roughly three times as many tokens for the same content. The rule is to look at the distribution of your inputs rather than the mean, and to sample deliberately from the parts that differ: the long tail, the other language, the awkward format. Twenty random items rarely contain the outlier, and if the outliers are numerous they dominate the bill.

  2. The hundred-item comparison found eight articles the small model got right and the large one wrong. What causes that group, and why does it matter to the design?

    One answer

    Large models are better on average, not uniformly better, and they overthink constrained tasks: here by choosing a more precise category than the fixed list allowed. The group matters because it is always larger than people expect, and it is the evidence that a cascade is not a compromise: escalating only the flagged cases can score as well as or better than the large model everywhere, while costing a fraction. It also warns against assuming that a disagreement between the two models means the expensive one is right.

  3. Why did the living-person flag go to the expensive model regardless of the confidence word?

    One answer

    Because the escalation signal that matters most is the cost of being wrong, which is a business decision rather than a technical one. A confidence word from a model is uncalibrated and correlates only usefully with correctness, which is adequate for routing a tag and not adequate where the failure is a legal read that never happens. Anything whose error costs money, safety or a legal exposure goes to the expensive model by rule, not by confidence.

Test yourself6 questions on this modulePractice. Nothing is recorded and no score is kept.
  1. 1

    Your work is reading fifty-page reports and answering in about three hundred words. Which number on a pricing page decides your bill?

  2. 2

    You measure twenty real items, multiply by fifty thousand, and get a figure. What does this module say to do next?

  3. 3

    Your request begins with fixed instructions, then a reference document, then today’s date, then the question. Why does prompt caching save you almost nothing?

  4. 4

    You run a hundred items through a small and a large model. Which group of results is usually larger than people expect, and what does it mean?

  5. 5

    Which property of a task decides whether one of these tools pays for itself?

  6. 6

    A free tier’s answers get shallower across an afternoon and you conclude the product has become worse this week. What has probably happened?

Open models and your own hardware

9 lessons · 1 h 13

You will be able toWork out what your own machine will run including context and cache, read a model card and licence well enough to decide whether to build on it, choose a quantisation and format deliberately, compare hosted open-model providers on speed, precision, context and data terms, and set a routing rule between local and hosted work you can apply without thinking.

  1. 5.1The open models8 min
  2. 5.2Running a model on your own machine9 min
  3. 5.3Working out what your machine will run9 min
  4. 5.4Reading a model card before you download8 min
  5. 5.5Choosing a quantisation8 min
  6. 5.6Renting an open model instead of running it8 min
  7. 5.7The licence is a business decision8 min
  8. 5.8When running it yourself is the wrong answer7 min
  9. 5.9A working setup with two models8 min
An illustrative case, built from documented patternsA laptop, a graphics card, and a clause in the engagement letterA chartered accountant in Surat working out how to summarise four years of a client’s ledgers without the ledgers leaving her office

Nikita Shah practises alone and keeps twelve clients. The largest is a garment exporter whose engagement letter contains an ordinary clause: client records may not be disclosed to any third party without written consent. She had never thought of it as an AI clause, because it was drafted in 2019.

The work in front of her was four years of ledger narrations: about forty thousand lines, most of them abbreviated, inconsistent between the two people who had entered them, and full of names. She wanted a model to group them, flag the ones that did not match a head of account, and draft the management letter that came out of it.

Her machine is a three-year-old laptop with sixteen gigabytes of memory and no separate graphics card.

Three options were on the table. A business-tier subscription at about twenty-two hundred rupees a month buys a contract saying the content is not used for training, a data processing agreement and a retention setting. All of that is real and none of it answers the engagement letter, because a data processing agreement does not make a disclosure into something other than a disclosure. A hosted open model is cheaper and faster and is also a third party. And a machine that would run something larger locally (thirty-two gigabytes, ninety-five thousand rupees) is four years of the subscription in a year where she was also replacing a printer and had just started paying a part-time assistant.

So she installed Ollama and an eight-billion-parameter instruct model on the laptop she had. In chat it was excellent: drafting, rewriting, tidying her own notes, about fourteen tokens a second, entirely adequate.

Then she pasted a single year of narrations into it. Thirty-eight thousand tokens. The machine slowed to a crawl, the fans came on, and the first word of the answer took over a minute to appear.

She assumed the model was too big for the machine. It was not. The weights were about four and a half gigabytes and had been fine all week. What had changed was the working memory for the conversation, which grows with the length of the context and on a document of that size had come to rival the weights themselves, on top of the runtime and everything else the laptop was already holding.

The decision in front of her was whether to buy the machine now, or to split the work (local for anything carrying the client’s identity, hosted for everything else) and accept that the ledger job would run in small batches overnight over several days rather than in an afternoon.

The case for buying was not only speed. Her practice is her own, there is no IT department, and she disliked the position of having the confidentiality of her largest client depend on a setting she might change by accident. A machine that could hold a larger model comfortably would let her stop thinking about the boundary altogether, which is a real thing to want.

The case against was the part that is easy to leave out of the arithmetic. Ninety-five thousand rupees is four years of the subscription she was comparing it against, and the subscription’s model improves underneath her for nothing while the machine holds still. A colleague in Rajkot had bought a graphics card eighteen months earlier for exactly this reason and had since spent a lost weekend on a driver problem after an operating system upgrade, and another evening re-downloading every model he had because a file format had moved on.

There was a third option nobody had put on the table, which was to ask the client. Nikita had not considered it because she had framed the whole question as a technical one about where computation happens, when the clause in the engagement letter is about consent and consent is something a client can give. The exporter’s finance director is a person she speaks to most weeks.

What would you have tried before spending ninety-five thousand rupees, and what would you have put in the letter?

How it played out

She did three things, none of which cost money.

She reduced the runner’s context setting from its large default to eight thousand tokens, switched the conversation cache to eight-bit, and closed the browser, which on its own returned about two and a half gigabytes. The eight-billion model then handled the narrations in batches of two hundred lines at about twelve tokens a second, running overnight across four nights. No purchase was made.

She wrote to the client. One paragraph: which service she proposed to use for non-identifying analysis, which tier, what would and would not be sent, and a request for written consent. The reply came in two days and asked for the same paragraph in a form the exporter could show their own auditor.

And she found that the habit of writing the role rather than the name (the supplier, the customer, the director) meant most of the management-letter drafting never needed the local model at all, because nothing identifying was in it.

At her September review a four-billion model released that spring did the narration job on the same laptop at about thirty tokens a second. The case for the ninety-five thousand rupee machine was weaker in September than it had been in March, which is the usual direction.

Worth arguing about

  1. Why did a model that worked perfectly in chat crawl on a year of narrations, and what are the two cheapest fixes?

    One answer

    Because the weights are not the only thing in memory. The KV cache, the model’s working memory for the context so far, grows with the amount of text in front of it, and on a long document it can rival the size of the weights. The machine then swaps to disk and speed collapses. The two cheapest fixes are to lower the context setting, which most runners default to something far larger than short questions need, and to quantise the cache to eight-bit, which roughly halves that column for a negligible quality cost. Both are settings, not purchases.

  2. A no-training commitment and a data processing agreement are genuine things to buy. Why did they not answer the question the engagement letter asked?

    One answer

    Because the clause was about disclosure to a third party, and sending records to a hosted service is a disclosure however good the terms are. A contract changes what the recipient may do with the material; it does not change the fact that the material was sent. It also does not move responsibility: Nikita is the one deciding to send it, and the agreement is evidence of due diligence rather than a transfer of liability. The two routes that actually answer the clause are consent from the client, or computation that never leaves the machine.

  3. The machine would have cost four years of the subscription. Name two things that make that comparison worse than it looks.

    One answer

    First, the hardware only fits the model sizes it fits, and it will be superseded while the subscription’s model improves under it at no extra cost. Second, running a model locally carries an ongoing cost nobody quotes: runners update and change behaviour, formats evolve, a driver stack breaks after an operating system upgrade, and better models arrive constantly, so the file installed today is quietly becoming the wrong choice. It is about an hour a month if kept up and a lost weekend if not.

Test yourself6 questions on this modulePractice. Nothing is recorded and no score is kept.
  1. 1

    A model card says the weights are released under a community licence. What have you not necessarily been given?

  2. 2

    An eight-billion model runs comfortably on your sixteen-gigabyte laptop in chat, then crawls when you paste in a fifty-page report. Why?

  3. 3

    You have memory for either a large model crushed to two bits or a smaller one at four. Which is the better default?

  4. 4

    Why does this module tell you to prefer safetensors files over the older weight format?

  5. 5

    Two providers serve the same open model name at different prices. What should you settle before comparing those prices?

  6. 6

    The hybrid rule routes work by what the material contains rather than by how hard the task looks. Why?

Data, terms and the law

9 lessons · 1 h 11

You will be able toEstablish for any tool whether your content is trained on, retained or read by people and whether that covers your tier, redact material so the sensitive part is never sent, recognise which questions about ownership and legality are genuinely unresolved, and write the one-page record of tools and boundaries that a client or regulator would ask for.

  1. 6.1Who reads what you type8 min
  2. 6.2Reading the terms in ten minutes8 min
  3. 6.3What a business agreement actually buys8 min
  4. 6.4Your country, your rules9 min
  5. 6.5Who owns what it produces8 min
  6. 6.6Redaction that actually works8 min
  7. 6.7Secrets, and what not to paste7 min
  8. 6.8Accounts, sharing and devices7 min
  9. 6.9What your workplace probably has not decided8 min
An illustrative case, built from documented patternsTwo hundred report cards and a parent’s questionA school in Ranchi the week after term reports went home, trying to answer a parent who asked where her daughter’s comments had been written

Class teachers at the school write four to six lines of comment for every pupil at the end of term, about forty pupils a class, nine classes in the middle school. It takes an evening a class and everybody dislikes it.

In September a teacher, Mr Barla, started pasting the term’s marks and his rough notes into a free assistant and asking for a polished comment. The results were better than what he had been writing, and they were better still when he included the pupil’s name, because the sentences read more naturally. By December most of the middle school’s comments were being drafted this way. Nobody had decided anything. There had been no meeting.

At the parents’ evening a mother who works as a software tester asked a straightforward question: which service was used, and what happens to what was typed into it.

Sister Mary Grace, the principal, did not know. The IT coordinator found out in ten minutes. A free consumer tier. A setting in the account, switched on by default, permitting the conversations to be used to improve the model. A retention statement that said content is kept as long as necessary, which is not a period anybody can plan around. And a paragraph, as almost every policy has, saying that samples and flagged conversations may be read by people.

The vice-principal wanted the practice stopped that evening. The position is defensible and it is what a parent would expect to hear.

Mr Barla’s position was that the comments were better, that thirty-one teachers had just been handed back an evening a term, and that a ban would not return them to handwriting. It would move the practice to personal accounts on personal phones at home, where the school would know nothing about it at all.

Then a specific fact came out that changed the register of the conversation. One of Mr Barla’s comments had explained a pupil’s drop in attendance by referring to her father’s illness, because that was the honest explanation and he wanted the comment to be fair. He had typed it, with her name, into a free consumer account, with no policy in front of him and no ill intent whatsoever.

Three things followed from that one comment and none of them was about the assistant. The information was about a third person who was not the school’s pupil. It was health information, which in most data protection regimes sits in a more protected category than an address or a mark. And it had been typed into an account whose settings permitted the conversation to be used for training, by a teacher who had never been told there was a decision to make.

The IT coordinator raised a separate point that the meeting had not reached. Thirty-one teachers were doing this on whatever account they already had, which for most of them was the account they also use at home. Report comments, family circumstances, and the teacher’s own private conversations were accumulating in the same history, on devices that in several cases are shared with children and spouses. Memory features in some of these products carry context from one conversation into the next, which means a teacher who has spent a term discussing pupils may find that context appearing in a personal question.

The vice-principal’s answer to all of this was that it strengthened her case. The coordinator’s view was that it strengthened the opposite one, because every fact she had just listed was a fact the school had learned by asking, and a ban would end the asking rather than the practice.

The cost on one side was a rule that somebody had to write, a route that somebody had to find, and a check that thirty-one teachers were following it, in December, in the last fortnight of a term. The cost on the other was a ban that looked responsible to a parents’ meeting and would produce a worse, invisible version of the same practice by February.

What would you have written, and what would you have said to the parent?

How it played out

Neither the ban nor the shrug. Sister Mary Grace wrote a single page in an afternoon and it was in use before the next term began.

The approved account turned out to cost nothing: the school’s existing productivity licence already included an assistant on business terms that nobody had switched on. The rule had five lines. No pupil names, no family circumstances and no medical information: roles only, so the pupil and a pupil whose attendance fell in October. Every comment is read by the class teacher before it is entered. Anything touching home circumstances is written by hand and typed nowhere. And the last line named a person to tell when something had already gone wrong, and said plainly that reporting it quickly was expected rather than punished.

Four teachers came forward in the first week. One of them was Mr Barla.

The parent received a written answer naming the service, the tier and the terms as they stood that week, with a dated screenshot kept in the school’s file. She asked for it in writing, which is how the school came to have the paragraph it now gives to anybody who asks.

The comments written from roles rather than names read exactly as well as the ones written from names. The model had never been using the name for anything.

Worth arguing about

  1. Why was it wrong to stop at whether the service trains on the school’s data?

    One answer

    Because training, retention and human review are three separate promises with three separate answers, and companies answer the first loudly and the other two quietly. A provider can truthfully say it does not train on your data while keeping conversations for a period and permitting staff to read flagged ones. For a school the retention and review answers are the ones that matter, because the material is a child’s personal data and in one case her father’s health, and the honest mental model is not that a machine reads it and forgets.

  2. The vice-principal’s ban was defensible. Why would it probably have left the school worse off?

    One answer

    Because the tools had already been adopted and the work had already got easier. A blanket ban does not return the practice to handwriting; it moves it to personal accounts on personal devices with worse terms and no visibility, which is the well-documented outcome. The school would have traded a risk it could manage for one it could not see, while believing it had made a decision. The workable position is named tools, a clear line about what is sensitive, a check before anything goes out, and a route for reporting mistakes.

  3. What did the dated screenshot buy the school that the policy page itself did not?

    One answer

    Evidence of what was true when the school relied on it. Terms change without notice, and a parent or a regulator asking next year will be asking about the position this term. A dated capture of the settings page and of the paragraph relied on is the only record of what was agreed to at the time; the current live page will show whatever it shows then. For anything that matters, a dated copy held by an archive service is better still, because it is not the school’s own screenshot.

Test yourself6 questions on this modulePractice. Nothing is recorded and no score is kept.
  1. 1

    A provider states plainly that it does not train on your data. Which question does that statement leave open?

  2. 2

    Why is ‘does this company train on my data’ not a well-formed question?

  3. 3

    You upgrade to a business tier with a data processing agreement and a contractual no-training commitment. What has not changed?

  4. 4

    Several regimes restrict decisions made about a person purely by automated means. What separates a permitted use from a restricted one?

  5. 5

    A PDF has a black rectangle drawn over a name before it is sent out. What is the state of the name?

  6. 6

    You realise you have pasted a live API key into a chat. What is the first thing to do?

Beyond the chat box

11 lessons · 1 h 29

You will be able toJudge a tool in any of the main non-chat categories on the property that actually separates them (legible text, verifiable citations, licensed data, visible code, consent and retention) name the free path that does the same job, and identify the failure mode specific to that category before it costs you.

  1. 7.1Choosing an image tool9 min
  2. 7.2Transcription and translation8 min
  3. 7.3Voice and speech tools8 min
  4. 7.4Video tools, generated and edited8 min
  5. 7.5Research and search tools9 min
  6. 7.6Documents, PDFs and OCR8 min
  7. 7.7Spreadsheets and data tools8 min
  8. 7.8Meeting notetakers7 min
  9. 7.9Office suite assistants8 min
  10. 7.10Agents and automation platforms8 min
  11. 7.11Specialist and industry tools8 min
An illustrative case, built from documented patternsTwelve thousand licence applications and a question nobody askedA municipal corporation office in Jaipur evaluating a quotation to digitise a decade of trade licence applications

The office holds twelve thousand four hundred trade licence applications from 2016 onwards, about fifteen thousand eight hundred pages. They are needed as searchable records with eight fields each: licence number, applicant name, trade category, ward, date of application, fee paid, date of issue and renewal status.

A vendor quoted fourteen rupees a page for what the proposal called AI-powered document intelligence. That is about two lakh twenty thousand rupees, six weeks, and a contract with somebody accountable at the end of it. The demonstration used three clean forms from 2023 and read all eight fields correctly from each.

A junior assistant, Rakesh Meena, asked one question in the meeting. Are these scans, or are some of them files the corporation’s own licensing software printed?

Nobody knew, so they checked. Four thousand nine hundred of the files had been generated by the office’s own system after 2021 and carried a text layer. A free command-line tool read every character of them exactly, in seconds, with no recognition involved and no possibility of a digit being misread. The remaining seven thousand five hundred were genuine scans of paper forms: many completed by hand, some skewed, a number of them photocopies of photocopies.

So the quotation covered four thousand nine hundred files for which the answer was already sitting in the file.

The decision that followed had a cost on both sides. The vendor’s price covered everything, arrived on a date, and came with somebody to complain to. Doing it in-house with free tools meant Rakesh and one colleague spending about five weeks of their own time in an office that is short-staffed, and if it went wrong there would be nobody to complain to but themselves.

Rakesh’s supervisor, Mrs Sharma, raised the point that settled the shape of the work. Two of the eight fields are numbers. A wrong trade category is an annoyance that somebody will notice and correct. A wrong fee in a licence record is a discrepancy against the treasury’s books that may not surface for years.

And nobody had tested the vendor’s tool on the worst material. Handwritten applicant names in Devanagari on a faint photocopy are a different problem from a clean printed form from 2023, and the demonstration had not contained one. When Mrs Sharma asked for a demonstration on twenty files the office would choose, the vendor’s representative agreed readily, which was itself informative, and then asked for a week.

Rakesh spent an evening of his own on the four thousand nine hundred text-layer files to find out whether the in-house route was fantasy. It was not. Exact extraction took minutes. The part that was not trivial was the fields: the forms changed layout twice between 2016 and 2025, the ward is written in three different formats, and about a fifth of the applications record the fee in words as well as figures, which disagree in a handful of cases.

That last discovery mattered more than the vendor’s price. It meant that whichever route the office took, somebody was going to have to decide what happens when a form says one thing in figures and another in words, and no tool was going to decide it for them.

Mrs Sharma’s own position was that the office had been offered a service and had not yet worked out what it was buying. Two lakh twenty thousand rupees for pages, or a database the treasury would accept? Those are different products and only one of them was in the quotation.

What would you have quoted for, and what would you have written into the contract?

How it played out

They split the job, which neither side had proposed.

The four thousand nine hundred text-layer files were extracted in-house in two days. Exact extraction, then a model asked to pull the eight named fields from the extracted text rather than from a picture of the page. Total cost in usage: about nine hundred rupees.

The seven thousand five hundred scans went to the vendor, re-quoted at the same rate for nine thousand one hundred pages: one lakh twenty-seven thousand instead of two lakh twenty.

Two conditions went into the contract. The vendor returns the recognised text alongside the extracted fields, so any disputed record can be traced back to what was actually read. And every batch is checked by a rule the office wrote itself: the fee column is summed by month and compared against the treasury’s own monthly receipts. The first batch was out by forty-one thousand rupees in one month: sixty-one records in which a handwritten five had been read as a six on fees ending in five hundred. That batch was re-run.

Handwritten names stayed the weak part. The office accepted it deliberately, because every record also carries a printed licence number, so a wrong name is recoverable from the number. That was written down as a decision rather than discovered later as a fault.

Worth arguing about

  1. One question moved the quotation by nearly a lakh. What was it, and why does it come before every other tool choice for documents?

    One answer

    Whether the PDF already contains a text layer or is a picture of a page. If the text is there, extraction is exact and free, and takes seconds. If it is not, you need recognition, which is approximate and can change a digit without saying so. Sending a text-layer file through a recognition or vision route is strictly worse in every dimension: slower, more expensive, and capable of introducing an error where the exact characters were already sitting in the file. It takes five seconds to check.

  2. The monthly fee check caught sixty-one errors in one batch. Why is that check worth more than a better recognition engine?

    One answer

    Because extraction errors are silent. A record with a wrong digit looks exactly like a correct one, and no amount of engine quality removes the possibility on faint handwriting. A validation that compares extracted totals against a figure known independently turns a silent error into a visible one, in a single line of arithmetic, on every batch. It is the document equivalent of printing row counts before and after an operation, and it catches the errors that reading the output never would.

  3. The office accepted a known weakness on handwritten names. What made that acceptable here, and when would it not be?

    One answer

    It was acceptable because each record carries an independently printed licence number, so a misread name is recoverable rather than lost, and because the limit was recorded as a decision with a reason rather than left to be discovered as a failure. It would not be acceptable where the name is the only key, where a wrong name has a consequence that cannot be reversed, or where nobody has written down that the weakness exists, at which point the next person to use the data will reasonably assume it is sound.

Test yourself6 questions on this modulePractice. Nothing is recorded and no score is kept.
  1. 1

    Before choosing any tool for a PDF, this module says to establish one thing first. What is it?

  2. 2

    Which habit catches more errors in data work than any other?

  3. 3

    Why does a tool grounded only on documents you supplied fail more safely than a search-grounded assistant?

  4. 4

    If each step of an autonomous loop is right ninety-five per cent of the time, what happens over twenty steps, and what follows?

  5. 5

    A meeting ends without a decision and the notetaker’s summary records one. Why, and what is the defence?

  6. 6

    Someone says they want AI video for their small business. What do they most likely need?

Living with it

9 lessons · 1 h 07

You will be able toTurn repeated work into saved instructions kept in your own files, migrate to a replacement tool when one is withdrawn without losing your working setup, measure a tool’s effect on your own work honestly enough to act on it, and separate the parts of any AI comparison that expire within months from the structural facts that do not.

  1. 8.1From chatting to a workflow8 min
  2. 8.2Keeping your work portable7 min
  3. 8.3Two tools, and a date in your calendar7 min
  4. 8.4When your tool is withdrawn7 min
  5. 8.5Introducing a tool to other people8 min
  6. 8.6Measuring whether it actually helped8 min
  7. 8.7Keeping up without drowning7 min
  8. 8.8When the right answer is not to use it8 min
  9. 8.9What changes, and what does not7 min
An illustrative case, built from documented patternsA deprecation notice in filing seasonA one-person bookkeeping practice in Thrissur reading an email about a model retirement three weeks before the busiest month of the year

Divya Menon keeps books and files returns for thirty-four small businesses. Over two years she has built six saved instructions that carry most of her repetitive work: an explainer she sends clients when their purchase register does not match what their suppliers filed, a bank-narration classifier, a payment reminder in Malayalam and English, a skeleton for a director’s report, a query list generated from a trial balance, and a plain-language note explaining a departmental notice.

They all run through an API from a free front-end on her desktop, against a pinned model snapshot rather than a moving name. She pinned it eighteen months ago, after a Tuesday morning when the classifier changed its mind about cash withdrawals and she lost a day finding out why.

The notice said the snapshot would be withdrawn in ninety days. It named a successor. The prices were different in both directions: input cheaper, output dearer, which for her work (long inputs, short outputs) probably meant slightly less.

Three weeks separated her from the start of filing season, which is six weeks of fourteen-hour days.

The argument for migrating immediately was that ninety days sounds long and contains the season. A regression found on the eighteenth of the month, with returns due, is not the same event as a regression found in June.

The argument against was that she did not have an evening. She was onboarding two clients that fortnight, and the snapshot would keep working throughout the season regardless. June is quiet. June is when you do this sort of thing.

There was a third item in the notice that she nearly skipped, because it was about the API and the API stores nothing of hers. But her front-end keeps its own conversation database on her own machine, along with the reference documents she has attached to it over two years, and she had never once tested whether its export produced anything usable.

She also noticed, reading the notice a second time, that it had arrived at the email address on the account. She is the only person in the practice, so the address is hers. It occurred to her that this is not true of most of her clients, several of whom have software accounts in the name of a relative who set them up and no longer reads that mailbox. A notice like this one, sent to such an address, is a notice nobody receives.

The pricing line deserved a second look too. Input cheaper and output dearer sounds neutral and is not, because it depends entirely on the shape of the work. Hers is long inputs and short outputs (a trial balance in, a query list out) so the change was probably slightly in her favour. A colleague who generates long client reports from short briefs would have read the same two numbers and found the opposite.

What she did not have was the thing the rest of this decision rested on. Her prompt file had eleven items and she had been meaning to add a twelfth since last year. Two of the eleven were prompts she had quietly rewritten after a tool failed them, which she now realised meant those two were no longer testing anything.

There was also a question she could not answer about her own setup. Six saved instructions lived in the front-end’s own database, and their only copy was in there. She had written them, refined them over two years, and never once pasted them into a file of her own.

What would you have done with the three weeks, and what would you have refused to do until June?

How it played out

She spent ninety minutes on a Sunday and did not migrate.

She ran her prompt file (eleven prompts, not the twelve she had meant to build) through the successor. Nine were indistinguishable from the old model’s output. Two regressed, and both in the same way. The classifier and the client explainer had been relying on a length and a shape the old model produced without ever being told to: under about two hundred words, short paragraphs, no bullet lists. The successor wrote longer and reached for lists, and a client letter in bullet points is not what her clients expect from her.

The fix took twenty minutes. She took three outputs she had liked from the old model, wrote down what they had in common that her instruction did not say, and added four lines: under a hundred and eighty words, no lists, second person, one question at the end. Both prompts then passed.

She then stopped. The successor was recorded in her instruction file with the date and the exact model string, the old snapshot kept running through the season because it still worked and she now knew the replacement was safe, and the switch happened on the first Monday of June with nothing to discover.

The export was the other finding. It produced her conversations and not the files she had attached to them. She moved the reference documents into an ordinary folder that afternoon, which took ten minutes.

Worth arguing about

  1. Both regressions had the same cause. What was it, and why is it the usual cause after a model change?

    One answer

    The old model inferred something the instruction never stated. A prompt tuned over months accumulates implicit expectations: a length nobody specified because it always did that, a format it happened to fall into, an assumption about the domain. A new model has different defaults, so the prompt no longer carries enough. The fix is to make the implicit explicit: take three outputs you liked from the old tool, write down what they had in common that the prompt does not say, and add those lines. It resolves most migration regressions in about twenty minutes and is far cheaper than changing vendor.

  2. She tested the successor at once and migrated in June. Why is that better than either migrating immediately or waiting until June to test?

    One answer

    Testing immediately converts an unknown into a known while there is still time to act on it: if the successor had been genuinely worse, she would have had ninety days to look at other providers or an open model rather than three days in the middle of filing season. Migrating immediately would have spent an evening she did not have on a change that could safely wait. Separating the test from the switch gets the information early and the disruption late, which is the point of reading a deprecation notice properly rather than reacting to it.

  3. The export was missing the attachments. Why is finding that out in March better than in the week she decides to leave?

    One answer

    Because in March it is a ten-minute filing job and in the week of leaving it is a discovery. Exports differ in what they contain (some omit attachments, some omit project contexts, some produce a data file with no way to read it) and the data deadline in a withdrawal is often earlier than the shutdown date and never later. Testing the export in the first week, while leaving is still easy, is what converts a switch from a fortnight of rebuilding into an afternoon of pasting.

Test yourself6 questions on this modulePractice. Nothing is recorded and no score is kept.
  1. 1

    Which part of a saved instruction does most of the work, and is the part people leave out?

  2. 2

    Two different models give the same answer to a factual question. How much does that agreement tell you?

  3. 3

    A deprecation notice arrives. Why does exporting your data come before testing the successor?

  4. 4

    Why is ‘messages sent to the assistant’ a poor measure of whether a tool helped?

  5. 5

    Which of these is worth interrupting your month for, rather than waiting for the six-month review?

  6. 6

    What separates a principled decision not to use a tool from an untested objection?

What this course is

A straight, comparative look at the AI tools people actually use: ChatGPT, Claude, Gemini, Copilot, and the open models you can download. What genuinely separates them, what each free tier really gives you, when paying is worth it, what happens to what you type, and how to re-check all of it in six months when the answers have moved.

Who wrote it

Founder and series editor: Dr Mustafa Mun. Written by AI models to a written standard. Exam keys checked blind by a second model: 3,665 of 3,666 agreed. Academic review invited.

More in Use it in your work

  1. AI at Work73 lessonsThe tasks it genuinely helps with, the ones it quietly ruins, and the line you must never cross.
  2. AI for Teachers57 lessonsFor teachers who now have to teach and use AI, often with no training and no projector.
  3. Working in AI85 lessonsThe roles that exist, what they pay, and how people get in without a famous degree.
  4. How Software Development Changed87 lessonsWriting code got cheap. Knowing what to build did not.
  5. AI for a Small Business88 lessonsTwo or three tasks, honestly measured. Not a new department.
  6. AI for Students73 lessonsHow to use these tools and still end up knowing things.