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Glossary entry tool-use

Tool use

When an AI engine decides to invoke a web-search / web-fetch tool mid-conversation to ground its answer.

Filed under
Techniques

Definition

Tool use (or function calling) is when a language model decides on the fly to invoke an external action (like a web search or URL fetch) to answer a query. Anthropic's web_search and OpenAI's web_search_preview are tools. The model decides per-turn whether to invoke; not every query triggers a fetch. This is the boundary between 'training-data answer' and 'cited grounded answer'.

Example

User asks Claude 'what's Stripe's current pricing'. Claude invokes web_search tool → fetches stripe.com/pricing → cites the result.

How to optimize

Be the fetchable canonical source. Public, indexable, fast-rendering pages with up-to-date pricing/specs/numbers get cited when the tool fires.

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