Claude Web Search MCP Server

Instructions

Implementation Reference

• src/index.ts:41-72 (schema)

  Tool schema definition for web_search, including input schema with parameters for query, maxResults, allowedDomains, and blockedDomains.
  const WEB_SEARCH_TOOL: Tool = { name: "web_search", description: "Search the web for real-time information about any topic. Use this tool when you need up-to-date information that might not be available in your training data, or when you need to verify current facts.", inputSchema: { type: "object", properties: { query: { type: "string", description: "The search query to look up on the web" }, maxResults: { type: "number", description: "Maximum number of search results to return (default: 5)" }, allowedDomains: { type: "array", items: { type: "string" }, description: "Only include results from these domains" }, blockedDomains: { type: "array", items: { type: "string" }, description: "Never include results from these domains" } }, required: ["query"] } };
• src/index.ts:88-92 (registration)

  Registration of the web_search tool by returning it in the ListToolsRequestSchema handler.
  server.setRequestHandler(ListToolsRequestSchema, async () => { return { tools: [WEB_SEARCH_TOOL] }; });
• src/index.ts:95-171 (handler)

  The handler for CallToolRequestSchema that executes the web_search tool by invoking Anthropic Claude API with web_search_20250305 tool, processing the results, and returning formatted search results.
  server.setRequestHandler(CallToolRequestSchema, async (request: any) => { try { const { name, arguments: args } = request.params; if (name !== "web_search") { throw new Error(`Unknown tool: ${name}`); } if (!args || typeof args !== 'object') { throw new Error("No arguments provided"); } const { query, maxResults = 5, allowedDomains, blockedDomains } = args as any; if (!query || typeof query !== 'string') { throw new Error("Invalid query parameter"); } // Prepare the web search tool configuration const webSearchTool = { type: "web_search_20250305", name: "web_search", max_uses: maxResults }; // Add domain filtering if provided if (allowedDomains && Array.isArray(allowedDomains) && allowedDomains.length > 0) { (webSearchTool as any).allowed_domains = allowedDomains; } if (blockedDomains && Array.isArray(blockedDomains) && blockedDomains.length > 0) { (webSearchTool as any).blocked_domains = blockedDomains; } // Create a Claude message with the web search const response = await anthropic.messages.create({ model: "claude-3-7-sonnet-latest", max_tokens: 1024, messages: [ { role: "user", content: query } ], // @ts-ignore - Ignoring TypeScript error since Claude API does support this tools: [webSearchTool] }); // Extract and format the search results let results = ""; for (const item of response.content) { if (item.type === 'text') { results += item.text + "\n\n"; } else if (item.type === 'web_search_tool_result' && 'content' in item && Array.isArray(item.content)) { results += "### Search Results\n\n"; for (const result of item.content) { if (result.type === 'web_search_result') { results += `- [${result.title}](${result.url})\n`; results += ` Last updated: ${result.page_age || 'Unknown'}\n\n`; } } } } // Return the formatted results return { content: [{ type: "text", text: results.trim() }] }; } catch (error) { console.error('Error performing web search:', error); return { content: [{ type: "text", text: `Error performing web search: ${(error as Error).message}` }], isError: true }; } });