WebSearch tool description
CLI Claude Code, interactive mode, seeded with anonymous feature flags, v2.1.284. The text the model is given for this tool, line by line, with each line marked against the previous capture taken the same way. 15 model strings share this prompt, byte for byte.
Lines271,344 characters
Moved+1−1 against v2.1.283
Sent to15model strings get this description
Copies2distinct descriptions under this name
Parameters31 of them required
Every tool→every description on this arm
2 genuinely different descriptions of this tool
Plain text · sha256 71bd4c734533
The description, line by line
27 lines Line numbers are v2.1.283 on the left and this capture on the right.
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- Allows Claude to search the web and use the results to inform responses
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- Provides up-to-date information for current events and recent data
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- Returns search result information formatted as search result blocks, including links as markdown hyperlinks
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- Use this tool for accessing information beyond Claude's knowledge cutoff
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- Searches are performed automatically within a single API call
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CRITICAL REQUIREMENT - You MUST follow this:
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- After answering the user's question, you MUST include a "Sources:" section at the end of your response
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- In the Sources section, list all relevant URLs from the search results as markdown hyperlinks: [Title](URL)
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- This is MANDATORY - never skip including sources in your response
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- Example format:
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[Your answer here]
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Sources:
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- [Source Title 1](https://example.com/1)
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- [Source Title 2](https://example.com/2)
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Usage notes:
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- Domain filtering is supported to include or block specific websites
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- Web search is only available in the US
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IMPORTANT - Use the correct year in search queries:
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- The current month is September 2026. You MUST use this year when searching for recent information, documentation, or current events.
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- The current month is (provided in the conversation below). You MUST use this year when searching for recent information, documentation, or current events.
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- Example: If the user asks for "latest React docs", search for "React documentation" with the current year, NOT last year
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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"
}