🎯 The 60-Second Check That Catches AI's Made-Up Facts

AI gets things wrong at exactly the same volume and confidence as it gets things right. No stammer, no hedge, no shifty look. The invented figure arrives in the same tidy sentence as the correct one.

Which means “read it carefully” is useless advice. Careful reading finds typos. It does not find a plausible number.

So stop reading for errors. Make the errors label themselves on the way out.

The move: make it mark its own working

One instruction does most of the job. You tell Claude to write [CHECK] next to anything it isn’t solid on, as it writes, rather than smoothing over the gap.

Nick this one, paste it above any factual job:

You're drafting something I'm going to put in front of a client, so I need to know which bits are solid and which bits you're filling in.

The job: [e.g. "a one-page summary of what changed in the rules on late payment interest, for my invoice terms page"]
What I already know: [paste anything you have, or "nothing"]

As you write, follow this convention without exception:
- Any figure, date, price, law, deadline, statistic, company name or quote you are not certain of gets [CHECK] written immediately after it, inline, in the draft itself.
- If you genuinely don't know something, write [CHECK] and the gap. Do not fill it with something plausible.

Give me:
1. The draft, with [CHECK] markers in place.
2. A numbered list of every [CHECK], and for each one: what exactly needs confirming, and the specific place I should look (a named official site, my own records, the contract, the client).
3. The three claims in here that would embarrass me most if they were wrong, flagged whether or not they carry a [CHECK].
4. Finish with the final version only, [CHECK] markers still in, ready for me to work through.

Rules: British English, plain language, no filler. Be over-cautious. I would much rather see twenty [CHECK] markers than one confident invention. Do not remove a marker to make the draft read better.

Ask me up to three questions before you start.

Why this beats asking afterwards. Asking “was any of that made up?” makes Claude re-read a finished, fluent draft and judge it, which is a rigged test: it wrote the thing, and the thing reads well. Marking as it goes catches the gap at the moment it was papered over.

You’ll find the same [CHECK] convention in Ask Your Google Drive Anything, for the same reason. It’s worth using everywhere until it’s a reflex.

The audit, for things already drafted

For anything you wrote yesterday, or that came out of a chat before you’d read this.

Nick this one:

Audit what you just gave me before I use it. I'm about to send this to a paying client.

Go through it claim by claim and sort every factual statement into three groups, most doubtful first:
1. HONESTLY UNSURE. Could be a guess. Say what made it shaky.
2. PROBABLY RIGHT. Solid, worth a glance.
3. CERTAIN. You'd stake the work on it.

Then:
4. For everything in groups 1 and 2, tell me exactly where to confirm it: the named source, not "check online".
5. Search the web for the ones that are current or local (prices, rules, deadlines, opening times) and tell me what you found, including where you found nothing.

Rules: British English, be strict with yourself. If you cannot find a source for a claim, say so plainly instead of reasoning your way around it. A claim with no traceable source is decoration, and I'd rather bin it than defend it.

If it searches and comes back empty on a claim, that claim goes. A fact you cannot trace is not a fact.

When to bother

Not everything needs this. Three moments where it isn’t optional:

Anything with a number in it. Prices, dates, percentages, deadlines. The more precise it sounds, the more suspicious it deserves to be. “Around a third” is usually a safe pattern. “34.7% according to a 2023 study” is decoration until proven otherwise.

Anything leaving your chat with your name on it. The proposal, the newsletter, the pricing page, the post. A wrong date in your notes costs nothing. The same wrong date on a client’s quote costs the client relationship.

Anything about money, tax or contracts. Claude has read the rules of many countries at once and they blur. Add “UK specifically, and search the web to confirm the current position” to those questions, and treat what comes back as the briefing rather than the ruling.

Make it permanent

Turn memory on (Settings, then the memory option) and say this once:

Remember this: whenever you're writing anything for me that contains figures, dates, prices, laws or quotes, mark anything you're not certain of with [CHECK] as you write, and list them at the end. Don't wait for me to ask.

From then on it starts doing this on its own, which is the difference between a habit that exists and a habit that happens.

The honest bit

There’s something faintly circular about asking a system that can guess confidently to grade its own guessing, and occasionally it will be confidently wrong about being confident. Web search helps a lot with anything current. It doesn’t make this airtight.

So keep one rule on top: anything where being wrong costs real money, or has someone else’s name attached, gets confirmed by an official source or a qualified human. Same rule you’d apply to a capable new subcontractor. Trust, plus receipts.

Tonight

Take the last thing Claude wrote that you actually sent, and run the audit prompt on it. Whatever comes back in group 1 is the reason this guide exists.

Where this goes next. That’s one habit that keeps your work safe to send. The Claude Kickstart builds the rest of them in around your actual trade, five real jobs handed over properly. £47, one weekend.