Last verified 23 September 2026. Claude takes PDF, Word and other office files, up to 20 per chat. Projects work on every plan, even free. Sharing one with colleagues needs a Team or Enterprise plan. PubMed's citation finder is free. Details for experts at the end of this book.

The idea in one page

Sort by destination, not by feel. Before you check anything, ask where the output goes.

The step up from Level 1 is the red row. When a colleague follows your bench sheet, they trust you, not the tool. So they won't check it. You have to.

The four errors to look for first. Most errors in AI output fall into four kinds.

1. Numbers. Values, units, totals, dates and thresholds get changed, rounded or borrowed from another sentence.
2. References. A citation with real-looking authors, journal and year that doesn't exist, or exists but says something else.
3. Claims about your document. "According to the terms…" followed by something the terms never say.
4. Missing conditions. Summaries drop the exception, the deadline, the "only if" and the "more than". This is the hardest one to see, because nothing on the page looks wrong.

The five-step check for red output.

1. Find the line. For every material claim, meaning every claim someone will act on, find the sentence in the source that supports it. Ask the assistant to quote it, then find that quote yourself with Ctrl+F, the search box in any document or browser. If you can't find it, the claim is unsupported.
2. Redo the arithmetic. Recompute every number from the source values. Check units, and what each percentage is a percentage of.
3. Open every reference. Look it up in PubMed (the free database of life-science papers), the journal or the named document. If you can't find it in two minutes, treat it as invented.
4. Look for what's missing. Read the source's headings, exceptions and deadlines, and ask: which of these did the summary drop?
5. Read it as the person who'll act on it. What would they do differently because of this sentence? That's where a wrong word costs most.

Asking the assistant "Are you sure?" doesn't count. It will apologise or reassure you, with no new information. Asking it to quote its source is different: it gives you a string you can search for.

The check note. Your colleague can't see your check unless you write it down. Attach a short note: source title, version or date, and for each claim that matters, the quote and where it is. Unknowns are written as unknown. It takes five minutes, and it means the next person can check you in two.

Worked example: two teams, four quadrants

The method comes from T01-L01 · From Idea to Working Result: The Four-Quadrant Method. Here it is for a bench sheet, then for a customer FAQ.

Lab: a bench sheet for the new technician

Structure it. Sara, a postdoc, needs a one-page sheet for a new technician who starts on Monday. "He needs the inclusion and exclusion rules for protocol P-04 at the bench. A good result: a page he can follow without opening the protocol." She calls it red: he'll act on it without checking.

Understand it. She creates a Claude project, a workspace that keeps files and instructions together for every chat. With the + button on the right of the project's page she adds the protocol, then asks for the one-page sheet. Then, before she trusts it, she asks five questions she can answer from the protocol herself. The protocol reads, in part: "Include samples collected between 08:00 and 10:00 with a recorded storage temperature of 4 °C. Exclude samples stored for more than 72 hours or missing a collection timestamp. Mix each included sample for 30 seconds. Record two measurements and report their mean. If the two values differ by more than 5%, do not report a mean; flag the sample for review."

Three of five are right, and the two errors are the kind that change what happens at the bench. Something else strikes her: the technician has no way to check the sheet himself. That sends her back to Structure it: "A one-page sheet where every rule carries its protocol section, so he can check any line in ten seconds. And one line at the top with the protocol version."

Choose tools. She stays with what the group already has: a Claude project with the protocol attached, shared with the group. On the project's page she clicks Set project instructions and adds one instruction, which then applies to every chat in the project: "For every rule, give the protocol section and quote the sentence it comes from. If the protocol doesn't say, write 'not in the protocol'." She considers ChatGPT, which the institute also offers, and sees no reason to switch: the check matters more than the tool. The sheet cites two papers for the 72-hour limit, so PubMed's Single Citation Matcher goes on her list for step 3.

Build it. She regenerates the sheet and runs the five steps. Each quote turns up with Ctrl+F in the protocol. One of the two papers is real. The other has a plausible title and authors, and PubMed finds nothing, so she deletes it. The sheet had also dropped the 4 °C storage condition, and she puts it back. Then she tests it on the person who matters: the technician reads the sheet and checks two rules of his choice against the protocol, using the section numbers. He finds both in under a minute. At the top of the sheet: "From P-04 version 3, checked 23 September by Sara. If the protocol changes, this sheet is out of date."

What it taught her: the first draft needed two fixes, but the lasting change was the section numbers. They turned a sheet only she could vouch for into one anyone could check.

Company: an FAQ for four colleagues who answer customers

Structure it. Tom leads a customer service team of four at a lab-supplies distributor. A key supplier has sent new service terms, and his team gets questions about them every day. "A one-page FAQ my colleagues can answer customers from, without reading the terms each time." Red: customers will act on what his team says.

Understand it. He attaches the terms to the team's assistant and asks for the FAQ, then checks five answers against the text. The terms say, in part: "Standard orders may be cancelled without charge until 17:00 on the next business day. Custom orders cannot be cancelled after written production approval. Report damaged deliveries within five calendar days, with the order number and one photograph. The supplier will acknowledge a complete damage report within two business days. Replacement timing is agreed after inspection."

Four answers are right. The fifth says replacements arrive "within two business days". The number is in the terms, but it answers a different question: it belongs to the acknowledgement. The terms don't promise any replacement date. Checking whether the number appears somewhere would have missed this. You have to read what the sentence supports.

That changes his problem. The assistant wanted every question to have an answer. The real terms leave some open. Back to Structure it: "An FAQ that says plainly what the terms don't promise, so my team doesn't fill the gap."

Choose tools. The team's assistant with the terms attached, plus an instruction: "Quote the clause for each answer. If the terms don't answer a question, say so and suggest the wording 'we'll confirm after inspection'." For the day the supplier sends version 3, Word's Compare feature, on the Review tab, shows what changed between the two versions, so he knows which FAQ lines to re-check. No new tool.

Build it. He regenerates the FAQ and checks each quote. The replacement answer now reads: "The terms don't give a date. Say: we'll confirm a replacement date after the supplier inspects the damage." He saves the FAQ on the shared drive next to the terms, with a check note: terms version, date checked, clause for each answer. Then a colleague picks three answers and traces them to the clauses in the terms. She finds all three, and asks for one more entry: what to say when the photograph is missing. He adds it, marked "not in the terms, our own rule".

In both cases the fix that lasted was the same: every claim carries its source, and every gap is written down as a gap.

What goes wrong

Checking the draft and sending the fifth version. Symptom: you checked carefully, then asked the assistant to "make it shorter" three times, and a number changed on the way. Fix: check the version that leaves your desk. Any AI edit after the check reopens it.

Trusting a colleague's AI output because you trust the colleague. Symptom: a paragraph from someone careful goes into your report unchecked, and it's wrong. Fix: ask for their check note. If there isn't one, it's yellow at best, and you check it or mark it.

Finding the number, missing the meaning. Symptom: the value is in the source, so you tick it, but it answers a different question. Fix: read the whole source sentence, not just the number, and ask what it actually says.

Asking the assistant to approve itself. Symptom: "Are you sure?" gets you "Yes, I'm confident", or an apology and a new wrong answer. Fix: ask for the quote and find it yourself.

Dropping the check under time pressure. Symptom: "just this once" becomes the norm for urgent messages to customers or collaborators. Fix: cut the claim you can't check, or send it later. A shorter correct message beats a complete wrong one.

A check note nobody can use. Symptom: "checked against the protocol" with no version, no section, no date. Fix: source, version, date, and a location for each claim. Your colleague should be able to redo your check without asking you.

Do it yourself (30 minutes)

1. Structure it (5 min). Pick one AI-assisted deliverable that is due to colleagues this week. Write who will act on it and what they'll do. Give it a colour.
2. Understand it (10 min). Write five questions you can answer from the source yourself, and compare them with the draft. Note which of the four errors you find. If the errors change what the deliverable should be, rewrite your Structure it sentence.
3. Choose tools (3 min). Add one instruction: quote the source line for each claim, and say "not in the source" when it isn't. In a Claude project it goes under Set project instructions; in a plain chat, paste it at the top of your request. Decide where you'll check references.
4. Build it (12 min). Regenerate or fix the draft. Run the five steps on the final version. Write the check note. Give it to your colleague and ask them to trace three claims of their choice.

Exit check

What you hand in: a corrected team deliverable with a check note that gives:

• the source: title, version or date, and where it's stored;
• for each material claim: the quote and its page or section, or "not in the source";
• any arithmetic, written out so it can be redone;
• the open questions the source doesn't answer, marked as such;
• who checked it, and when.

It passes when a colleague traces three claims you didn't pick to the source without asking you, and finds each one.

Rule to remember

If a colleague will act on it, you've seen the source line, and so can they.

Details for experts

Checked on 23 September 2026. You don't need this to follow the book; it's for setting things up or answering a colleague.

Further reading and tools

Next books

• T01-L01 · From Idea to Working Result: The Four-Quadrant Method: the method this book works inside.
• T01-L03 · Build the Smallest Thing Your Colleagues Can Run Without You: choosing between chat, automation, app and agent.
• T04-L01 · Ask Your Own Documents and Check Every Citation: the same check for answers from your own files.
• T15-L01 · Use AI in Your Research and Say Exactly How: recording what AI did in research work.
• T02-L02 · Set Up Projects a Colleague Can Pick Up: projects and files, so the source is always attached.

Tools

• Claude: Taught. The project with the protocol attached and the quote-the-source instruction.
• ChatGPT: Taught. Works the same way for the company example.
• PubMed: Taught. Single Citation Matcher for checking references.
• Perplexity: Catalogued. Shows sources with its answers; open them before you trust them.