Introducing web search on the Anthropic API (via) Anthropic's web search (presumably still powered by Brave) is now also available through their API, in the shape of a new web search tool called web_search_20250305.
You can specify a maximum number of uses per prompt and you can also pass a list of disallowed or allowed domains, plus hints as to the user's current location.
Search results are returned in a format that looks similar to the Anthropic Citations API.
It's charged at $10 per 1,000 searches, which is a little more expensive than what the Brave Search API charges ($3 or $5 or $9 per thousand depending on how you're using them).
I couldn't find any details of additional rules surrounding storage or display of search results, which surprised me because both Google Gemini and OpenAI have these for their own API search results.