MCP Server Proxy

A proxy server that connects to multiple MCP servers and provides a unified interface for tool access.

Features

Connect to multiple MCP servers simultaneously
Support for multiple configuration profiles
Tool name prefixing with server names
Run in either stdio or SSE mode
Profile-based configuration management

Configuration

Create configuration files for each profile in the format config.<profile>.json. For example:

// config.developer.json
{
  "mcpServers": {
    "kubernetes": {
      "command": "npx",
      "args": ["mcp-server-kubernetes"]
    }
  }
}

// config.personal.json
{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/Users/mirilale/Desktop"
      ]
    }
  }
}

Installation

npm install

Usage

Command Line Options

The server can be started with various command-line options:

# Start with default settings
node dist/server.js

# Start with a specific profile
node dist/server.js --profile developer
# or
node dist/server.js -p developer

# Start in SSE mode
node dist/server.js --mode sse
# or
node dist/server.js -m sse

# Start in SSE mode with custom port and host
node dist/server.js --mode sse --port 8080 --host 0.0.0.0

# Combine options
node dist/server.js --profile developer --mode sse --port 8080

Available options:

-p, --profile <name>: Specify which profile to use (defaults to "default")
-m, --mode <mode>: Choose between "stdio" or "sse" mode (defaults to "stdio")
--port <number>: Set the port for SSE mode (defaults to 3000)
--host <host>: Set the host for SSE mode (defaults to "localhost")

Get help:

node dist/server.js --help

Tool Naming Convention

Tools are prefixed with their server name. For example:

A tool named read_file from the filesystem server becomes filesystem_read_file
A tool named get_pods from the kubernetes server becomes kubernetes_get_pods

SSE Mode Endpoints

When running in SSE mode, the server exposes the following endpoints:

GET /sse: Establishes an SSE connection
POST /messages: Handles tool requests (requires sessionId query parameter)

Example SSE client usage:

const eventSource = new EventSource("http://localhost:3000/sse");
eventSource.onmessage = (event) => {
  console.log("Received:", event.data);
};

Error Handling

The server provides detailed error messages including:

Profile loading errors
Server connection failures
Tool not found errors
Server disconnection errors

All errors include the current profile name for better context.

Development

# Install dependencies
npm install

# Build the project
npm run build

# Run in development mode
npm run dev:stdio:developer
# or
npm run dev:sse:developer

# Run with mpc inspector
npm run inspect

License

MIT