MCP Proxy Server

🚀 MCP Proxy Server

A proxy server that aggregates and provides multiple MCP resource servers through a single interface. This server acts as a central hub, capable of connecting and managing multiple MCP resource servers, exposing their combined functionality via a unified interface, routing requests to appropriate backend servers, and aggregating responses from multiple sources.

🚀 Quick Start

The MCP Proxy Server serves as a central hub, aggregating multiple MCP resource servers and offering a unified interface. It can connect and manage multiple MCP resource servers, expose their combined functionality, route requests to appropriate backend servers, and aggregate responses from multiple sources.

✨ Features

Resource Management

• Discover and connect to multiple MCP resource servers.
• Aggregate resources from all connected servers.
• Maintain a consistent URI scheme across servers.
• Handle resource routing and resolution.

Tool Aggregation

• Expose tools from all connected servers.
• Route tool calls to the appropriate backend servers.
• Maintain tool states and handle responses.

Prompt Handling

• Aggregate prompts from all servers.
• Route prompt requests to the appropriate backends.
• Handle multi - server prompt responses.

📦 Installation

When using with Claude Desktop, add the server configuration:

On MacOS: ~/Library/Application Support/Claude/claude_desktop_config.json On Windows: %APPDATA%/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "mcp-proxy": {
      "command": "/path/to/mcp-proxy-server/build/index.js",
      "env": {
        "MCP_CONFIG_PATH": "/absolute/path/to/your/config.json",
        "KEEP_SERVER_OPEN": "1"
      }
    }
  }
}

• KEEP_SERVER_OPEN keeps the SSE running when the client disconnects, which is useful for multiple clients connecting to the MCP proxy.

💻 Usage Examples

Configuration

The server requires a JSON configuration file specifying the MCP servers to connect to. Copy the example configuration and modify it as needed:

cp config.example.json config.json

Example configuration structure:

{
  "servers": [
    {
      "name": "Server 1",
      "transport": {
        "command": "/path/to/server1/build/index.js"
      }
    },
    {
      "name": "Server 2",
      "transport": {
        "command": "server2-command",
        "args": ["--option1", "value1"],
        "env": ["SECRET_API_KEY"]
      }
    },
    {
      "name": "Example Server 3",
      "transport": {
        "type": "sse",
        "url": "http://localhost:8080/sse"
      }
    }
  ]
}

The configuration file must be provided when running the server:

MCP_CONFIG_PATH=./config.json mcp-proxy-server

Development

Install dependencies:

npm install

Build the server:

npm run build

Development with auto - rebuild:

npm run watch

Development with continuous running:

# Standard input and output
npm run dev
# SSE
npm run dev:sse

Debugging

Since MCP servers communicate via stdio, debugging can be challenging. We recommend using MCP Inspector, which is available as a package script:

npm run inspector

The Inspector will provide a URL to access the debugging tools in the browser.