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  1. ahmadrosid created this gist Jun 28, 2025.
    347 changes: 347 additions & 0 deletions claude-web-search-tool.md
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    # Web search tool

    The web search tool gives Claude direct access to real-time web content, allowing it to answer questions with up-to-date information beyond its knowledge cutoff. Claude automatically cites sources from search results as part of its answer.

    Please reach out through our feedback form to share your experience with the web search tool.

    ## Supported models

    Web search is available on:

    - Claude Opus 4 ( `claude-opus-4-20250514`)
    - Claude Sonnet 4 ( `claude-sonnet-4-20250514`)
    - Claude Sonnet 3.7 ( `claude-3-7-sonnet-20250219`)
    - Claude Sonnet 3.5 (new) ( `claude-3-5-sonnet-latest`)
    - Claude Haiku 3.5 ( `claude-3-5-haiku-latest`)

    ## How web search works

    When you add the web search tool to your API request:

    1. Claude decides when to search based on the prompt.
    2. The API executes the searches and provides Claude with the results. This process may repeat multiple times throughout a single request.
    3. At the end of its turn, Claude provides a final response with cited sources.

    ## How to use web search

    Your organization’s administrator must enable web search in Console.

    Provide the web search tool in your API request:

    ```py
    import anthropic

    client = anthropic.Anthropic()

    response = client.messages.create(
    model="claude-opus-4-20250514",
    max_tokens=1024,
    messages=[
    {
    "role": "user",
    "content": "How do I update a web app to TypeScript 5.5?"
    }
    ],
    tools=[{
    "type": "web_search_20250305",
    "name": "web_search",
    "max_uses": 5
    }]
    )
    print(response)
    ```

    ### Tool definition

    The web search tool supports the following parameters:

    ```json
    {
    "type": "web_search_20250305",
    "name": "web_search",

    // Optional: Limit the number of searches per request
    "max_uses": 5,

    // Optional: Only include results from these domains
    "allowed_domains": ["example.com", "trusteddomain.org"],

    // Optional: Never include results from these domains
    "blocked_domains": ["untrustedsource.com"],

    // Optional: Localize search results
    "user_location": {
    "type": "approximate",
    "city": "San Francisco",
    "region": "California",
    "country": "US",
    "timezone": "America/Los_Angeles"
    }
    }
    ```

    #### Max uses

    The `max_uses` parameter limits the number of searches performed. If Claude attempts more searches than allowed, the `web_search_tool_result` will be an error with the `max_uses_exceeded` error code.

    #### Domain filtering

    When using domain filters:

    - Domains should not include the HTTP/HTTPS scheme (use `example.com` instead of `https://example.com`)
    - Subdomains are automatically included ( `example.com` covers `docs.example.com`)
    - Subpaths are supported ( `example.com/blog`)
    - You can use either `allowed_domains` or `blocked_domains`, but not both in the same request.

    #### Localization

    The `user_location` parameter allows you to localize search results based on a user’s location.

    - `type`: The type of location (must be `approximate`)
    - `city`: The city name
    - `region`: The region or state
    - `country`: The country
    - `timezone`: The IANA timezone ID.

    ### Response

    Here’s an example response structure:

    ```json
    {
    "role": "assistant",
    "content": [
    // 1. Claude's decision to search
    {
    "type": "text",
    "text": "I'll search for when Claude Shannon was born."
    },
    // 2. The search query used
    {
    "type": "server_tool_use",
    "id": "srvtoolu_01WYG3ziw53XMcoyKL4XcZmE",
    "name": "web_search",
    "input": {
    "query": "claude shannon birth date"
    }
    },
    // 3. Search results
    {
    "type": "web_search_tool_result",
    "tool_use_id": "srvtoolu_01WYG3ziw53XMcoyKL4XcZmE",
    "content": [
    {
    "type": "web_search_result",
    "url": "https://en.wikipedia.org/wiki/Claude_Shannon",
    "title": "Claude Shannon - Wikipedia",
    "encrypted_content": "EqgfCioIARgBIiQ3YTAwMjY1Mi1mZjM5LTQ1NGUtODgxNC1kNjNjNTk1ZWI3Y...",
    "page_age": "April 30, 2025"
    }
    ]
    },
    {
    "text": "Based on the search results, ",
    "type": "text"
    },
    // 4. Claude's response with citations
    {
    "text": "Claude Shannon was born on April 30, 1916, in Petoskey, Michigan",
    "type": "text",
    "citations": [
    {
    "type": "web_search_result_location",
    "url": "https://en.wikipedia.org/wiki/Claude_Shannon",
    "title": "Claude Shannon - Wikipedia",
    "encrypted_index": "Eo8BCioIAhgBIiQyYjQ0OWJmZi1lNm..",
    "cited_text": "Claude Elwood Shannon (April 30, 1916 – February 24, 2001) was an American mathematician, electrical engineer, computer scientist, cryptographer and i..."
    }
    ]
    }
    ],
    "id": "msg_a930390d3a",
    "usage": {
    "input_tokens": 6039,
    "output_tokens": 931,
    "server_tool_use": {
    "web_search_requests": 1
    }
    },
    "stop_reason": "end_turn"
    }
    ```

    #### Search results

    Search results include:

    - `url`: The URL of the source page
    - `title`: The title of the source page
    - `page_age`: When the site was last updated
    - `encrypted_content`: Encrypted content that must be passed back in multi-turn conversations for citations

    #### Citations

    Citations are always enabled for web search, and each `web_search_result_location` includes:

    - `url`: The URL of the cited source
    - `title`: The title of the cited source
    - `encrypted_index`: A reference that must be passed back for multi-turn conversations.
    - `cited_text`: Up to 150 characters of the cited content

    The web search citation fields `cited_text`, `title`, and `url` do not count towards input or output token usage.

    When displaying web results or information contained in web results to end users, inline citations must be made clearly visible and clickable in your user interface.

    #### Errors

    If an error occurs during web search, you’ll receive a response that takes the following form:

    ```json
    {
    "type": "web_search_tool_result",
    "tool_use_id": "servertoolu_a93jad",
    "content": {
    "type": "web_search_tool_result_error",
    "error_code": "max_uses_exceeded"
    }
    }
    ```

    These are the possible error codes:

    - `too_many_requests`: Rate limit exceeded
    - `invalid_input`: Invalid search query parameter
    - `max_uses_exceeded`: Maximum web search tool uses exceeded
    - `query_too_long`: Query exceeds maximum length
    - `unavailable`: An internal error occurred

    #### `pause_turn` stop reason

    The response may include a `pause_turn` stop reason, which indicates that the API paused a long-running turn. You may provide the response back as-is in a subsequent request to let Claude continue its turn, or modify the content if you wish to interrupt the conversation.

    ## Prompt caching

    Web search works with prompt caching. To enable prompt caching, add at least one `cache_control` breakpoint in your request. The system will automatically cache up until the last `web_search_tool_result` block when executing the tool.

    For multi-turn conversations, set a `cache_control` breakpoint on or after the last `web_search_tool_result` block to reuse cached content.

    For example, to use prompt caching with web search for a multi-turn conversation:

    ```py
    import anthropic

    client = anthropic.Anthropic()

    # First request with web search and cache breakpoint
    messages = [
    {
    "role": "user",
    "content": "What's the current weather in San Francisco today?"
    }
    ]

    response1 = client.messages.create(
    model="claude-opus-4-20250514",
    max_tokens=1024,
    messages=messages,
    tools=[{
    "type": "web_search_20250305",
    "name": "web_search",
    "user_location": {
    "type": "approximate",
    "city": "San Francisco",
    "region": "California",
    "country": "US",
    "timezone": "America/Los_Angeles"
    }
    }]
    )

    # Add Claude's response to the conversation
    messages.append({
    "role": "assistant",
    "content": response1.content
    })

    # Second request with cache breakpoint after the search results
    messages.append({
    "role": "user",
    "content": "Should I expect rain later this week?",
    "cache_control": {"type": "ephemeral"} # Cache up to this point
    })

    response2 = client.messages.create(
    model="claude-opus-4-20250514",
    max_tokens=1024,
    messages=messages,
    tools=[{
    "type": "web_search_20250305",
    "name": "web_search",
    "user_location": {
    "type": "approximate",
    "city": "San Francisco",
    "region": "California",
    "country": "US",
    "timezone": "America/Los_Angeles"
    }
    }]
    )
    # The second response will benefit from cached search results
    # while still being able to perform new searches if needed
    print(f"Cache read tokens: {response2.usage.get('cache_read_input_tokens', 0)}")
    ```

    ## Streaming

    With streaming enabled, you’ll receive search events as part of the stream. There will be a pause while the search executes:

    ```
    event: message_start
    data: {"type": "message_start", "message": {"id": "msg_abc123", "type": "message"}}
    event: content_block_start
    data: {"type": "content_block_start", "index": 0, "content_block": {"type": "text", "text": ""}}
    // Claude's decision to search
    event: content_block_start
    data: {"type": "content_block_start", "index": 1, "content_block": {"type": "server_tool_use", "id": "srvtoolu_xyz789", "name": "web_search"}}
    // Search query streamed
    event: content_block_delta
    data: {"type": "content_block_delta", "index": 1, "delta": {"type": "input_json_delta", "partial_json": "{\"query\":\"latest quantum computing breakthroughs 2025\"}"}}
    // Pause while search executes
    // Search results streamed
    event: content_block_start
    data: {"type": "content_block_start", "index": 2, "content_block": {"type": "web_search_tool_result", "tool_use_id": "srvtoolu_xyz789", "content": [{"type": "web_search_result", "title": "Quantum Computing Breakthroughs in 2025", "url": "https://example.com"}]}}
    // Claude's response with citations (omitted in this example)
    ```

    ## Batch requests

    You can include the web search tool in the Messages Batches API. Web search tool calls through the Messages Batches API are priced the same as those in regular Messages API requests.

    ## Usage and pricing

    Web search usage is charged in addition to token usage:

    ```
    "usage": {
    "input_tokens": 105,
    "output_tokens": 6039,
    "cache_read_input_tokens": 7123,
    "cache_creation_input_tokens": 7345,
    "server_tool_use": {
    "web_search_requests": 1
    }
    }
    ```

    Web search is available on the Anthropic API for **$10 per 1,000 searches**, plus standard token costs for search-generated content. Web search results retrieved throughout a conversation are counted as input tokens, in search iterations executed during a single turn and in subsequent conversation turns.

    Each web search counts as one use, regardless of the number of results returned. If an error occurs during web search, the web search will not be billed.

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