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Claude Code has two web tools: WebFetch for retrieving and analyzing specific URLs, and WebSearch for querying the web when information may be beyond Claude’s training cutoff.

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WebFetch

Fetches a URL, converts the HTML to markdown, and then processes the content using a small fast model with a prompt you provide. Returns the model’s response — not the raw page content.

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Parameters

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url
string
required
A fully-formed, valid URL. HTTP URLs are automatically upgraded to HTTPS.
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prompt
string
required
A natural-language prompt describing what to extract or analyze from the page content. The fetched content is passed to a secondary model along with this prompt, and the model’s response is returned.

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Behavior

  1. Claude fetches the URL and converts HTML to markdown.
  2. The markdown and the prompt are sent to a small, fast model.
  3. That model’s response is returned as the tool result.
Because a secondary model processes the content, the result is always a synthesized answer — not a raw dump of the page. If the content is very large, it may be summarized automatically.
WebFetch includes a 15-minute in-memory cache. Repeated calls to the same URL within that window return cached content without a network request.

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Redirects

When a URL redirects to a different host, the tool returns a special message indicating the redirect destination rather than following it automatically. Claude then makes a new WebFetch call with the redirect URL.

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Limitations

  • Read-only — does not submit forms or interact with pages
  • Not suitable for pages requiring authentication (login walls, paywalls)
  • For GitHub resources, prefer the gh CLI via Bash (e.g., gh pr view, gh issue view, gh api)
If an MCP-provided web fetch tool is available in your environment, it may have fewer restrictions and should be preferred over this built-in tool.

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Example usage

{
  "url": "https://docs.example.com/api/authentication",
  "prompt": "What authentication methods are supported and what headers are required?"
}

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WebSearch

Searches the web and returns results including titles, URLs, and a model-synthesized summary. Useful when information may be newer than Claude’s training data.
Web search is only available in the United States. It requires a compatible API provider (Anthropic first-party, Vertex AI with Claude 4.0+ models, or Foundry).

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Parameters

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query
string
required
The search query to execute. Minimum length: 2 characters.
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allowed_domains
string[]
When set, only return results from these domains. Cannot be combined with blocked_domains in the same request.Example: ["docs.python.org", "peps.python.org"]
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blocked_domains
string[]
Exclude results from these domains. Cannot be combined with allowed_domains in the same request.Example: ["w3schools.com"]

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Output

The tool returns search results as structured blocks containing:
  • Result titles and URLs
  • A synthesized summary produced by a model that has access to the search results
Claude is required to cite sources from web searches by appending a Sources: section with markdown hyperlinks to its response.

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Domain filtering

Use allowed_domains when you want results exclusively from trusted or authoritative sources:
{
  "query": "Python asyncio best practices 2024",
  "allowed_domains": ["docs.python.org", "realpython.com"]
}
Use blocked_domains to suppress low-quality or paywalled sources:
{
  "query": "React server components tutorial",
  "blocked_domains": ["medium.com"]
}

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Search limits

Each WebSearch invocation performs up to 8 individual web searches internally. Claude automatically refines queries as needed within that budget.

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Current date awareness

When searching for recent information, Claude includes the current year in search queries to avoid returning outdated results — for example, appending the year when searching for library documentation or current events.