Verifying a claim means checking it against something outside the chat. Asking the model to confirm its own answer does not count, because the same patterns that produced the claim will produce the confirmation. An outside source is anything the model did not write: a document you already have, a website you open yourself, a person who knows the subject, or a second tool that draws on different material.
The decision to trust or verify is not about how confident the answer sounds. It is about what happens if the answer is wrong. A low-stakes, familiar, easily checked task — rewording a sentence, explaining a common idea, drafting something you will review anyway — is safe to take at face value. A high-stakes or unfamiliar claim — a medical dose, a legal deadline, a statistic you will repeat, a citation you will publish — should be verified before you act on it.
A practical routine has three moves. First, scan the answer for unsolicited specifics and mark them. Second, ask what the cost would be if each marked detail were wrong. Third, check the expensive ones against an outside source, and leave the cheap ones alone. This keeps the effort proportional to the risk instead of treating every sentence as equally suspect.