All capabilities Research and the live web

Answer from the live web with citations attached

The model decides when to search, the API runs the searches, and the final answer carries source URLs, titles and the exact quoted span.

DocsOfficially documentedTestNot tested by benchr Quick · API Docs checked September 1, 2026

Claude APIClaude Opus 5Claude Sonnet 5Claude Opus 4.8+1

Overview

Returns web_search_result_location citations with url, title and up to 150 characters of cited text - and those citation fields do not count toward token usage.
Accepts an allowed_domains or blocked_domains list, so a research agent can be pointed at primary sources only.
From web_search_20260209 onward, writes and runs code to filter results before they enter the context window, which cuts token use on search-heavy runs.

01Add the tool and set max_uses. Simple factual questions use one to three searches; comparative research can use ten or more.
02Constrain the domains. For anything you intend to publish, an allowlist of official sources is the difference between research and aggregation.
03Send the assistant's content blocks back unchanged, including encrypted_content, or the next turn fails with a 400.
04Handle stop_reason: pause_turn by returning the paused message unchanged.

$10 per 1,000 searches on the Claude API, on top of standard token costs - and results consumed in a turn count as input tokens.
Provide allowed_domains or blocked_domains, never both; sending both returns a 400.
Not available on Amazon Bedrock. On Google Cloud and Azure-hosted Microsoft Foundry only the basic tool version works, without dynamic filtering.
An organisation administrator can disable web search entirely, in which case the request fails at validation rather than inside a result.

benchr has not run this capability. No test has been published. 1 self-reported run awaiting independent review.

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Source-check history

September 1, 2026DocsOfficially documentedFirst logged. Price per 1,000 searches, the three tool versions, citation structure and platform gaps read from the tool page.