browser-pool-mcp

Instructions

Implementation Reference

• index.js:301-315 (registration)

  Registration of the 'browser_navigate' tool using server.tool, which proxies the call to a browser client.

  server.tool('browser_navigate', 'Navigate to URL', { url: z.string() },
    async (args, extra) => {
      log(`[browser_navigate] called with args: ${JSON.stringify(args)}`);
      try {
        const result = await proxyToolCall('browser_navigate', args);
        log(`[browser_navigate] result: ${JSON.stringify(result).slice(0, 500)}`);
        if (!result.isError) {
          hasActivePage = true; // Mark page as active after successful navigation
        }
        return result;
      } catch (err) {
        log(`[browser_navigate] ERROR: ${err.message}\n${err.stack}`);
        throw err;
      }
    });

• index.js:209-240 (helper)

  The proxyToolCall function serves as the actual implementation handler that forwards tool execution requests (including 'browser_navigate') to the underlying MCP client.

  async function proxyToolCall(toolName, args) {
    log(`[proxyToolCall] ${toolName} with args: ${JSON.stringify(args)}`);
    const { client } = await getOrCreateInstance();
    log(`[proxyToolCall] got client for port ${assignedPort}`);
  
    // Update last used
    if (assignedPort && instances.has(assignedPort)) {
      instances.get(assignedPort).lastUsed = Date.now();
    }
  
    try {
      log(`[proxyToolCall] Calling client.callTool...`);
      const result = await client.callTool({ name: toolName, arguments: args || {} });
      log(`[proxyToolCall] Result type: ${typeof result}`);
      log(`[proxyToolCall] Result: ${JSON.stringify(result).slice(0, 500)}`);
  
      // The SDK returns { content: [...], isError?: boolean }
      // We need to return this same format
      if (result && result.content) {
        return result;
      }
  
      // Fallback: wrap in content array if needed
      return {
        content: [{ type: 'text', text: JSON.stringify(result) }]
      };
    } catch (error) {
      log(`[proxyToolCall] ERROR: ${error.message}\n${error.stack}`);
      return {
        content: [{ type: 'text', text: `Error: ${error.message}` }],
        isError: true
      };