Know What Claude Can't Know

A clear mental model of the boundary between what Claude actually knows — general knowledge up to its training cutoff, plus whatever you give it — and what it cannot know: recent events, live data, and anything private to you or your organisation.

Most misplaced trust comes from not knowing where this line is. Claude reasons fluently about things it has no current data on, which reads as confidence. Holding the boundary in mind tells you when to trust an answer outright (reasoning, explanation, code structure) and when to supply the facts yourself or verify — recent news, today's prices, your internal numbers. It turns 'is this right?' into a targeted check rather than blanket doubt.

Any time the answer depends on a recent event, a fast-changing fact, or information specific to your situation. If being wrong would matter and the fact is fresh or private, verify.

For stable, general knowledge and reasoning tasks well within training, constant re-verification is wasted effort. And once you've pasted the source material in, Claude is working from that — treat it as reading your document, not recalling the world.

For this question, first tell me which parts you can answer from general knowledge and which depend on recent or private information you can't have. For the latter, tell me what to provide or verify rather than guessing. Then answer the parts you can, and clearly mark any claim I should check.

You ask about a library's current recommended API. Claude answers from training but flags that the library may have changed since its cutoff and tells you which page to confirm against. You paste the current docs, and now its answer is grounded in today's reality rather than last year's.

When freshness is essential, give Claude the current material directly — paste the docs, the report, the data — so it reasons over your source instead of its memory. Supplying the facts converts a knowledge-limit problem into a reading-comprehension task, which is Claude's strength.

• Trusting confident-sounding specifics — exact figures, dates, versions — for things past the cutoff without checking.
• Assuming Claude can see your files, systems, or the live web unless a tool explicitly gives it access.
• Over-correcting into distrust of everything, re-verifying settled general knowledge and wasting time.