MCP Server Proxy

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