Citations (grounded answers)

Citations connect what the model says to where it came from. In a grounded answer, each claim links to a document, page, or passage that was in the model's context. They turn an answer from trust me into here's the evidence, and they let users jump to the source when the stakes are high.

There are two ways to get them. You can ask the model to reference passage IDs or quote text in a structured format and then check those quotes against the sources in your code. Or you can use a provider's citations feature: on the Claude API, enabling citations on document blocks returns answer text broken into pieces with references to the cited text and its location. Note that Claude's citations and structured outputs can't be combined in the same request.

Citations only build trust if they're real. A model can cite a passage that doesn't say what it claims, so verify that quoted text exists and spot-check that it supports the claim, ideally with faithfulness evals. In the interface, make citations easy to inspect and handle answers with no supporting source differently.

Also cite at the right granularity: a link to a 40-page PDF is barely better than none.