Master MCP Server

# STDIO Server Support The Master MCP Server now supports STDIO-based MCP servers in addition to HTTP-based servers. This allows you to aggregate both network-based and locally-running MCP servers through a single endpoint. ## Configuration To configure a STDIO server, use a `file://` URL in your server configuration: ```json { "servers": [ { "id": "stdio-server", "type": "local", "url": "file://./path/to/your/stdio-mcp-server.cjs", "auth_strategy": "bypass_auth", "config": { "environment": {}, "args": [] } } ] } ``` The Master MCP Server will automatically detect `file://` URLs and treat them as STDIO servers, starting them as child processes and communicating with them through stdin/stdout using JSON-RPC. ## How It Works 1. **Server Detection**: The Master MCP Server detects `file://` URLs and identifies them as STDIO servers 2. **Process Management**: STDIO servers are started as child processes 3. **Communication**: The Master MCP Server communicates with STDIO servers using JSON-RPC over stdin/stdout 4. **Capability Discovery**: The Master MCP Server discovers tools and resources from STDIO servers 5. **Request Routing**: Tool calls and resource reads are routed to the appropriate STDIO servers ## Benefits - **Unified Interface**: Access both HTTP and STDIO servers through a single MCP endpoint - **Process Isolation**: Each STDIO server runs in its own process for better isolation - **Automatic Management**: The Master MCP Server handles process lifecycle management - **Seamless Integration**: STDIO servers appear as regular MCP servers to clients ## Requirements - STDIO servers must implement the MCP protocol using JSON-RPC over stdin/stdout - STDIO servers should follow the MCP specification for initialization and capability discovery - STDIO servers must be executable Node.js scripts (`.js` or `.cjs` files) ## Example STDIO Server Here's a simple example of a STDIO server: ```javascript // Simple STDIO server that implements the MCP protocol // Save this as stdio-mcp-server.cjs and make it executable with chmod +x ``` process.stdin.on('data', async (data) => { try { const lines = data.toString().split('\n').filter(line => line.trim() !== ''); for (const line of lines) { const request = JSON.parse(line); // Handle initialize request if (request.method === 'initialize') { const response = { jsonrpc: '2.0', id: request.id, result: { protocolVersion: '2025-06-18', capabilities: { tools: { listChanged: true }, resources: { listChanged: true } }, serverInfo: { name: 'example-stdio-server', version: '1.0.0' } } }; process.stdout.write(JSON.stringify(response) + '\n'); } // Handle other requests... } } catch (err) { const errorResponse = { jsonrpc: '2.0', id: null, error: { code: -32700, message: 'Parse error', data: err.message } }; process.stdout.write(JSON.stringify(errorResponse) + '\n'); } }); ``` Make sure to make your STDIO server executable: ```bash chmod +x ./path/to/your/stdio-mcp-server.cjs ```