#!/usr/bin/env node
/**
* MCP Connection Tester
*
* This script tests the connection between the MCP Inspector and your MCP server
* to diagnose and fix connection issues.
*/
import { spawn, exec } from 'child_process';
import { fileURLToPath } from 'url';
import path from 'path';
import fs from 'fs';
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
class MCPConnectionTester {
constructor() {
this.projectRoot = path.resolve(__dirname, '..');
this.serverProcess = null;
this.inspectorProcess = null;
}
async test() {
console.log('🔍 Testing MCP Server Connection...\n');
try {
// Step 1: Verify build
await this.verifyBuild();
// Step 2: Test server startup
await this.testServerStartup();
// Step 3: Test inspector connection
await this.testInspectorConnection();
console.log('\n✅ All tests passed! MCP connection should work.');
} catch (error) {
console.error('\n❌ Connection test failed:', error.message);
await this.provideSolution(error);
} finally {
await this.cleanup();
}
}
async verifyBuild() {
console.log('📦 Verifying build...');
const buildPath = path.join(this.projectRoot, 'build', 'index.js');
if (!fs.existsSync(buildPath)) {
console.log('⚠️ Build not found, building project...');
await this.execCommand('npm run build');
console.log('✅ Project built successfully');
} else {
console.log('✅ Build verified');
}
}
async testServerStartup() {
console.log('\n🚀 Testing MCP server startup...');
return new Promise((resolve, reject) => {
this.serverProcess = spawn('node', ['build/index.js'], {
cwd: this.projectRoot,
stdio: ['pipe', 'pipe', 'pipe']
});
let output = '';
let hasStarted = false;
const timeout = setTimeout(() => {
if (!hasStarted) {
reject(new Error('Server startup timeout - server may not be starting properly'));
}
}, 10000);
this.serverProcess.stdout.on('data', (data) => {
output += data.toString();
console.log('📝 Server output:', data.toString().trim());
// Check for successful startup indicators
if (output.includes('Gmail MCP server connected') ||
output.includes('Server started') ||
output.includes('listening') ||
output.includes('ready')) {
hasStarted = true;
clearTimeout(timeout);
console.log('✅ MCP server started successfully');
resolve();
}
});
this.serverProcess.stderr.on('data', (data) => {
const errorOutput = data.toString();
console.log('⚠️ Server stderr:', errorOutput.trim());
// Check for critical errors
if (errorOutput.includes('Error:') || errorOutput.includes('EADDRINUSE')) {
clearTimeout(timeout);
reject(new Error(`Server startup error: ${errorOutput}`));
}
});
this.serverProcess.on('exit', (code) => {
clearTimeout(timeout);
if (code !== 0 && !hasStarted) {
reject(new Error(`Server exited with code ${code} before startup completed`));
}
});
// Send a test message to see if server responds
setTimeout(() => {
if (this.serverProcess && !this.serverProcess.killed) {
try {
// Send a simple JSON-RPC message to test connectivity
const testMessage = JSON.stringify({
jsonrpc: "2.0",
id: 1,
method: "initialize",
params: {
protocolVersion: "2024-11-05",
capabilities: {},
clientInfo: { name: "connection-tester", version: "1.0.0" }
}
}) + '\n';
this.serverProcess.stdin.write(testMessage);
} catch (error) {
console.log('ℹ️ Could not send test message:', error.message);
}
}
}, 2000);
});
}
async testInspectorConnection() {
console.log('\n🔗 Testing Inspector connection...');
// Kill the server process since inspector will start its own
if (this.serverProcess) {
this.serverProcess.kill('SIGTERM');
await this.sleep(1000);
}
return new Promise((resolve, reject) => {
this.inspectorProcess = spawn('npm', ['run', 'inspector'], {
cwd: this.projectRoot,
stdio: ['pipe', 'pipe', 'pipe']
});
let output = '';
let hasConnected = false;
const timeout = setTimeout(() => {
if (!hasConnected) {
reject(new Error('Inspector connection timeout - could not establish connection to MCP server'));
}
}, 15000);
this.inspectorProcess.stdout.on('data', (data) => {
output += data.toString();
console.log('📝 Inspector output:', data.toString().trim());
// Check for successful connection
if (output.includes('MCP Inspector is up and running') ||
output.includes('Created server transport') ||
output.includes('Connected to MCP server')) {
hasConnected = true;
clearTimeout(timeout);
console.log('✅ Inspector connected to MCP server successfully');
resolve();
}
});
this.inspectorProcess.stderr.on('data', (data) => {
const errorOutput = data.toString();
console.log('⚠️ Inspector stderr:', errorOutput.trim());
// Check for connection errors
if (errorOutput.includes('Connection Error') ||
errorOutput.includes('ECONNREFUSED') ||
errorOutput.includes('proxy token is correct')) {
clearTimeout(timeout);
reject(new Error(`Inspector connection error: ${errorOutput}`));
}
});
this.inspectorProcess.on('exit', (code) => {
clearTimeout(timeout);
if (code !== 0 && !hasConnected) {
reject(new Error(`Inspector exited with code ${code} before connection established`));
}
});
});
}
async provideSolution(error) {
console.log('\n🔧 Providing solution based on error...\n');
const errorMessage = error.message.toLowerCase();
if (errorMessage.includes('timeout') || errorMessage.includes('connection')) {
console.log('💡 **Connection Issue Solutions:**');
console.log('');
console.log('1. **Use the Robust Inspector (Recommended):**');
console.log(' npm run inspector:robust');
console.log('');
console.log('2. **Manual Steps:**');
console.log(' a) Clean up processes: npm run inspector:cleanup');
console.log(' b) Build project: npm run build');
console.log(' c) Start robust inspector: npm run inspector:robust');
console.log('');
console.log('3. **Check for port conflicts:**');
console.log(' lsof -i :6274');
console.log(' lsof -i :6277');
console.log('');
console.log('4. **Verify MCP server configuration:**');
console.log(' - Check that build/index.js exists and is executable');
console.log(' - Verify no syntax errors in the server code');
console.log(' - Ensure all dependencies are installed');
}
if (errorMessage.includes('build') || errorMessage.includes('module')) {
console.log('💡 **Build Issue Solutions:**');
console.log('');
console.log('1. **Rebuild the project:**');
console.log(' npm run build');
console.log('');
console.log('2. **Check for TypeScript errors:**');
console.log(' npx tsc --noEmit');
console.log('');
console.log('3. **Reinstall dependencies:**');
console.log(' npm install');
}
if (errorMessage.includes('port') || errorMessage.includes('eaddrinuse')) {
console.log('💡 **Port Conflict Solutions:**');
console.log('');
console.log('1. **Kill processes using the ports:**');
console.log(' ./scripts/cleanup-inspector.sh');
console.log('');
console.log('2. **Use different ports:**');
console.log(' node scripts/robust-inspector.js --port 6275 --proxy-port 6278');
}
console.log('\n🎯 **Quick Fix Command:**');
console.log('npm run inspector:robust');
console.log('');
console.log('This will automatically handle most connection issues.');
}
async cleanup() {
console.log('\n🧹 Cleaning up test processes...');
if (this.serverProcess) {
this.serverProcess.kill('SIGTERM');
}
if (this.inspectorProcess) {
this.inspectorProcess.kill('SIGTERM');
}
// Wait for processes to exit
await this.sleep(1000);
console.log('✅ Cleanup completed');
}
sleep(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}
execCommand(command) {
return new Promise((resolve, reject) => {
exec(command, { cwd: this.projectRoot }, (error, stdout, stderr) => {
if (error) {
reject(error);
} else {
resolve({ stdout, stderr });
}
});
});
}
}
// Main execution
if (import.meta.url === `file://${process.argv[1]}`) {
const tester = new MCPConnectionTester();
tester.test().catch(error => {
console.error('❌ Test failed:', error);
process.exit(1);
});
}
export default MCPConnectionTester;
