Web Search

Use the built-in web search tool to give the model access to current information from the web.

Example request

Python

import os
import anthropic
 
client = anthropic.Anthropic(
    api_key="<API_KEY>",
    base_url='https://llm.onerouter.pro'
)
 
message = client.messages.create(
    model='claude-sonnet-4-5@20250929',
    max_tokens=2048,
    tools=[
        {
            'type': 'web_search_20250305',
            'name': 'web_search',
        }
    ],
    messages=[
        {
            'role': 'user',
            'content': 'What are the latest developments in quantum computing?'
        }
    ],
)
 
for block in message.content:
    if block.type == 'text':
        print(block.text)
    elif block.type == 'web_search_tool_result':
        print('Search results received')

TypeScript

Web search response format

When the model makes web search, the response includes tool use blocks:

{
  "id": "gen-1771662932-6kgZ7Ntv0LlaGlYSVVUT",
  "content": [
    {
      "id": "toolu_vrtx_01G9KmA4dCvqKcNZfWn9ebVq",
      "input": {
        "query": "latest developments quantum computing 2024"
      },
      "name": "web_search",
      "type": "tool_use"
    }
  ],
  "model": "claude-sonnet-4-5@20250929",
  "role": "assistant",
  "stop_reason": "tool_use",
  "stop_sequence": null,
  "type": "message",
  "usage": {
    "cache_creation_input_tokens": 0,
    "cache_read_input_tokens": 0,
    "input_tokens": 536,
    "output_tokens": 59,
    "server_tool_use": null,
    "service_tier": null
  }
}