browser-pool-mcp

Instructions

Implementation Reference

• index.js:452-458 (registration)

  Registration of the 'browser_file_upload' tool in the MCP server. It uses proxyToolCall to delegate the execution to a browser instance.

  server.tool('browser_file_upload', 'Upload files', {
    paths: z.array(z.string()).optional()
  }, async (args) => {
    const check = requireActivePage();
    if (check) return check;
    return proxyToolCall('browser_file_upload', args);
  });

• index.js:209-225 (helper)

  The helper function responsible for proxying the tool call to the active browser instance via the 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 }