What is the web search tool?
The web search tool is the specific function that lets an AI assistant fetch and read live web pages mid-conversation, and it's what actually produces a citation rather than a memorized guess.
The web search tool is a form of tool use: mid-conversation, the model can send a query to a search index, get back a set of pages, and read some of them before finishing its answer. Not every question triggers it. Some products only reach for it when a question seems to need current information; others call it by default; a few let the model decide on its own. That choice is usually fixed by the product's system prompt, not chosen fresh by the user.
This is worth understanding precisely because it's the actual source of most AI citations: when an assistant names a page, that's very often because this tool ran during that exchange and fetched it right then (see grounding), which has nothing to do with whether that same page was part of the model's training data. A page written well after a model's knowledge cutoff can still be cited, because it was fetched live, and a page the model did train on can go entirely uncited if this tool wasn't used, or didn't surface it, for that particular question.
Related
- GroundingGrounding is when a model answers using documents retrieved at the time of the question, rather than only from what it absorbed during training.
- CitationA citation is a source an AI assistant links or refers to in support of an answer it has given.
- Tool useTool use is a model's ability to call an outside function mid-answer, such as a search, a calculator, or a code runner, and fold whatever it gets back into its response.
- Retrieval-augmented generation (RAG)Retrieval-augmented generation is the technique of retrieving relevant documents and giving them to a model as context before it answers.
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