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Know which parts of an answer you can rely on

Use AI answers without passing on a mistake.

Next on this goal, last step: Make your checklist.

Lesson 4 of 8 · about 4–5 min reading + 4 min doing · last checked 2026-10-19

Recall

Recall (Lesson 1): No search, no link, and a rule that changed last month. What is the answer most likely to be?

Show the answerCheck your Lesson 1 answer before you start checking claims.

A guess from older training text. It may sound current, but nothing checked it.

The idea

A claim is checked when you find it in a source you opened.

Start with the claims that would hurt if wrong: numbers, dates, names, quotes and links. Asking the tool "are you sure?" just produces another reply.

Sort each claimThree claims point to three labelled bins: Found in a source I opened, use. Not found, cut or mark unchecked. Not a fact, just read it.A number or dateA name or quoteA linking phraseFound it: useNot found: cutor mark uncheckedNot a fact: read
Use a claim when you found it in a source you opened.

What counts as checked

You open the source, find the claim, and see that it says the same thing. That's a check. A reply that sounds sure is not a check. Neither is a link you haven't opened, or a second reply that agrees with the first.

Anthropic describes the problem as text that is "factually incorrect or inconsistent with the given context." The common name is hallucination: a reply that states something your prompt and sources don't support.

Check these first (our rule of thumb)

These are the claims your reader is most likely to act on.

Numbers and prices

One wrong digit changes the meaning, and the reader can't tell.

Dates and deadlines

A wrong day moves a meeting or misses a deadline.

Names and titles

The wrong person or job title is easy to miss and awkward to fix.

Quotes

A predicted quote looks exactly like a real one. Search the original for the exact words.

Links and citations

The page may exist and still not say what the reply claims.

Wording, tone and order matter too, but you can judge those by reading. Facts need a source.

When the tool searched for you

OpenAI's help is plain about it: "Search results and citations can be incomplete, outdated, or incorrect. Open a cited source to check that it supports the answer, review when it was published or updated, and use an authoritative source when accuracy matters." If a result looks wrong, it suggests you "ask ChatGPT to search again using a specific source, date, or location."

Claude's help says every search response includes citations, "so you can easily verify sources yourself," and advises: "Cross-reference cited sources."

Anthropic's guide for builders lists ways to reduce hallucinations, and still says: "Always validate critical information." A citation you haven't opened isn't a check.

When you can't find it

You have three honest options: cut the claim, mark it "unchecked", or ask someone who knows. Rounding it, or adding "about", doesn't make it checked. If most of a reply fails the check, start again with the source in the prompt (Lesson 3).

EXAMPLE · invented shop and policySee a three-line reply checked against the policy page, and two lines cut.

Before

The reply says: "Returns within 30 days of delivery. Shipping refunded in full. Contact us within 14 days." You forward all three lines to a customer.

After

You open the shop's policy page. "30 days from delivery" is there, so you keep it. "Shipping refunded" isn't there, so you cut it. "14 days" conflicts with the 30 days and isn't on the page, so you cut it too. Your reply now has one claim, and it's checked. The customer gets less, but nothing in it is wrong.

Practice

Step 1 (done for you): The reply quotes your refund policy in quotation marks. You have the policy open.Step 2: What's the fastest check?

How to check each kind of claim

Claim type How to check If you can't find it
Number or price The original table, invoice or page Leave it out
Date or deadline The source document or calendar Leave it out, or ask
Name or title An official page or directory Leave it out
Quote Search the original for the exact words Paraphrase, without quotation marks
Link or citation Open it, find the claim, check the date Drop the claim and the link
A fact with no source at all Lesson 1's three questions Treat it as a guess

Try it in your own AI tool (4 min)

Open a reply you used recently. Highlight every number, date, name, quote and link. Check the top two against a source. Cut whatever you can't find, or write "unchecked" next to it if you need to keep it for now.

Show the model answerCompare your highlights with ours: what matched, what you fixed, what's unchecked.

"5 highlights. The price matched the invoice. The deadline said Friday, but the email said Thursday, so I fixed it. 3 are marked 'unchecked'."

Check

Question 1 of 4. The reply cites a link for a statistic. When can you use the statistic?

Question 2 of 4. You ask, "Are you sure?" The tool replies, "Yes, I'm certain." What have you learned about the claim?

Question 3 of 4. A reply has eight claims, and you have five minutes before it goes to a client. Where do you start?

Question 4 of 4. A search answer cites a 2019 page for this year's rules. What do you do?

SourcesOpen the 5 source pages behind this lesson's claims, all checked 2026-10-19.
  1. Anthropic, Claude Help Center: "Enable and use web search"
  2. Anthropic, Claude Platform Docs: "Reduce hallucinations"
  3. OpenAI Help Center: "Searching the web with ChatGPT"

Go further, for builders

  1. Google AI for Developers: "Safety and factuality guidance"
  2. OpenAI API docs: "Optimizing LLM Accuracy" (LLM means large language model)