#!/usr/bin/env node
const { spawn } = require('child_process');
const net = require('net');
// Configuration
const MCP_GATEWAY_URL = process.env.MCP_GATEWAY_URL || 'http://127.0.0.1:4444';
const MCP_JWT_TOKEN = process.env.MCP_JWT_TOKEN;
// Ensure token is provided
if (!MCP_JWT_TOKEN) {
console.error('Error: MCP_JWT_TOKEN environment variable is not set.');
process.exit(1);
}
// Import fetch - try native first, fallback to node-fetch
let fetch;
try {
// Try native fetch first (Node.js 18+)
fetch = globalThis.fetch;
if (!fetch) {
// Fallback to node-fetch
const nodeFetch = require('node-fetch');
fetch = nodeFetch;
}
} catch (error) {
console.error('Error: Could not load fetch. Please install node-fetch: npm install node-fetch@2');
process.exit(1);
}
// Create a stdio bridge to MCP Gateway
class MCPStdioBridge {
constructor() {
this.connected = false;
this.init();
}
init() {
console.error('MCP Stdio Bridge starting...');
console.error('Gateway URL:', MCP_GATEWAY_URL);
// Buffer for handling partial messages
this.messageBuffer = '';
// Listen for messages from stdin
process.stdin.on('data', (data) => {
this.handleRawData(data.toString());
});
// Handle process termination
process.on('SIGINT', () => {
console.error('Shutting down MCP Stdio Bridge...');
process.exit(0);
});
}
handleRawData(rawData) {
this.messageBuffer += rawData;
// Split on newlines to handle multiple JSON messages
const lines = this.messageBuffer.split('\n');
// Keep the last incomplete line in the buffer
this.messageBuffer = lines.pop() || '';
// Process each complete line
for (const line of lines) {
const trimmed = line.trim();
if (trimmed) {
this.handleMessage(trimmed);
}
}
}
handleMessage(message) {
try {
const parsed = JSON.parse(message);
console.error('Received message:', JSON.stringify(parsed, null, 2));
// Handle 'initialize' method directly
if (parsed.method === 'initialize') {
this.sendMessage({
jsonrpc: '2.0',
id: parsed.id,
result: {
protocolVersion: parsed.params?.protocolVersion || '2025-06-18',
capabilities: {
tools: {
listChanged: true
},
resources: {
subscribe: true,
listChanged: true
},
prompts: {
listChanged: true
}
},
serverInfo: {
name: 'MCP Stdio Bridge',
version: '1.0.0'
}
}
});
return;
}
// Forward other messages to MCP Gateway
this.forwardToGateway(parsed);
} catch (error) {
console.error('Error parsing message:', error);
this.sendMessage({
jsonrpc: '2.0',
error: {
code: -32700,
message: 'Invalid JSON received'
},
id: null
});
}
}
async forwardToGateway(message) {
try {
// Handle different MCP methods
if (message.method === 'prompts/list') {
// Return empty prompts list for now
this.sendMessage({
jsonrpc: '2.0',
id: message.id,
result: {
prompts: []
}
});
return;
}
if (message.method === 'tools/list') {
// Get tools from gateway
const response = await fetch(`${MCP_GATEWAY_URL}/tools`, {
method: 'GET',
headers: {
'Authorization': `Bearer ${MCP_JWT_TOKEN}`
}
});
if (!response.ok) {
throw new Error(`Gateway responded with ${response.status}: ${await response.text()}`);
}
const tools = await response.json();
// Convert to MCP format
const mcpTools = tools.map(tool => ({
name: tool.name,
description: tool.description || '',
inputSchema: tool.inputSchema || {
type: 'object',
properties: {},
required: []
}
}));
this.sendMessage({
jsonrpc: '2.0',
id: message.id,
result: {
tools: mcpTools
}
});
return;
}
if (message.method === 'tools/call') {
// Execute a tool
const toolName = message.params.name;
const toolArgs = message.params.arguments || {};
const response = await fetch(`${MCP_GATEWAY_URL}/tools/${toolName}/execute`, {
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Authorization': `Bearer ${MCP_JWT_TOKEN}`
},
body: JSON.stringify(toolArgs)
});
if (!response.ok) {
throw new Error(`Gateway responded with ${response.status}: ${await response.text()}`);
}
const result = await response.json();
this.sendMessage({
jsonrpc: '2.0',
id: message.id,
result: {
content: [
{
type: 'text',
text: JSON.stringify(result, null, 2)
}
]
}
});
return;
}
// For other methods, return method not found
this.sendMessage({
jsonrpc: '2.0',
id: message.id,
error: {
code: -32601,
message: `Method not found: ${message.method}`
}
});
} catch (error) {
console.error('Error forwarding to gateway:', error);
this.sendMessage({
jsonrpc: '2.0',
error: {
code: -32603,
message: `Internal bridge error: ${error.message}`
},
id: message.id || null
});
}
}
sendMessage(message) {
// Use simple JSON output for MCP stdio
console.log(JSON.stringify(message));
}
}
// Start the bridge
new MCPStdioBridge();
