Sweep 22 Sep 2026 · 17:19Z Build v2.1.280 501 read Stable v2.1.267 Latest v2.1.280 Next v2.1.280 Feeds RSS JSON llms.txt Unofficial
Tool description

WebSearch, as sent

CLI Claude Code, interactive mode, v2.1.280. 10 model strings share this prompt, byte for byte.

Lines5312 characters
Moved+4−26 against v2.1.278
Reach10model strings receive this description
Copies2distinct descriptions under this name
Parameters31 of them required Tools in captureall of themevery description on this arm
2 genuinely different descriptions of this tool Plain text · sha256 da2fa36a5eab

The description, line by line

5 lines Line numbers are v2.1.278 on the left and this capture on the right.
1 Search the web. Returns result blocks with titles and URLs. US-only.
1 2
2 - Allows Claude to search the web and use the results to inform responses
3 - Provides up-to-date information for current events and recent data
4 - Returns search result information formatted as search result blocks, including links as markdown hyperlinks
5 - Use this tool for accessing information beyond Claude's knowledge cutoff
6 - Searches are performed automatically within a single API call
7
8 CRITICAL REQUIREMENT - You MUST follow this:
9 - After answering the user's question, you MUST include a "Sources:" section at the end of your response
10 - In the Sources section, list all relevant URLs from the search results as markdown hyperlinks: [Title](URL)
11 - This is MANDATORY - never skip including sources in your response
12 - Example format:
13
14 [Your answer here]
15
16 Sources:
17 - [Source Title 1](https://example.com/1)
18 - [Source Title 2](https://example.com/2)
19
20 Usage notes:
21 - Domain filtering is supported to include or block specific websites
22 - Web search is only available in the US
23
24 IMPORTANT - Use the correct year in search queries:
25 - The current month is September 2026. You MUST use this year when searching for recent information, documentation, or current events.
26 - Example: If the user asks for "latest React docs", search for "React documentation" with the current year, NOT last year
27
3 - The current month is September 2026 use this when searching for recent information.
4 - `allowed_domains` / `blocked_domains` filter results.
5 - After answering from results, end with a "Sources:" list of the URLs you used as markdown links.

What it accepts

3 parameters The JSON parameter schema sent beside this description, 577 characters of it. Name, type, then whether the client marked it required.
allowed_domains string[] optional Only include search results from these domains
blocked_domains string[] optional Never include search results from these domains
query string required The search query to use

sha256 78ab127603dd · the schema as the client sent it:

{ "$schema": "https://json-schema.org/draft/2020-12/schema", "additionalProperties": false, "properties": { "allowed_domains": { "description": "Only include search results from these domains", "items": { "type": "string" }, "type": "array" }, "blocked_domains": { "description": "Never include search results from these domains", "items": { "type": "string" }, "type": "array" }, "query": { "description": "The search query to use", "minLength": 2, "type": "string" } }, "required": [ "query" ], "type": "object" }