Router MCP server

The MCP Proxy Server acts as a central hub that aggregates multiple MCP resource servers through a single interface. It connects to multiple backend servers, exposes their combined capabilities, handles routing of requests, and aggregates responses from multiple sources.

Installation

Prerequisites

Before installing the MCP Proxy Server, ensure you have:

• Node.js installed
• npm (Node Package Manager)

Setup Configuration

Create a configuration file by copying the example:

cp config.example.json config.json

Edit the config.json file to specify the MCP servers you want to connect to:

{
  "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"
      }
    }
  ]
}

Running the Server

Run the MCP Proxy Server by specifying the config file path:

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

Integration with Claude Desktop

To use the MCP Proxy Server with Claude Desktop, you need to add the server configuration to Claude's settings.

Configuration Locations

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

Add Server Configuration

Add the following to your Claude Desktop configuration file:

{
  "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"
      }
    }
  }
}

Note: The KEEP_SERVER_OPEN environment variable keeps the SSE running even if a client disconnects, which is useful when multiple clients connect to the MCP proxy.

Using the Proxy Server

The MCP Proxy Server provides several key features that you can leverage:

Resource Management

The server automatically:

• Discovers and connects to multiple MCP resource servers
• Aggregates resources from all connected servers
• Maintains consistent URI schemes across servers
• Handles resource routing and resolution

Tool Integration

When using tools through the proxy:

• All tools from connected servers are exposed through a unified interface
• Tool calls are automatically routed to the appropriate backend server
• Tool state is maintained and responses are handled seamlessly

Prompt Handling

The proxy provides unified prompt handling:

• Aggregates prompts from all connected servers
• Routes prompt requests to appropriate backends
• Handles multi-server prompt responses

Debugging

If you encounter issues, you can use the MCP Inspector for debugging:

npm run inspector

This will provide a URL to access debugging tools in your browser, allowing you to inspect the communication between the proxy and its connected servers.

How to install this MCP server

For Claude Code

To add this MCP server to Claude Code, run this command in your terminal:

claude mcp add-json "mcp-proxy" '{"command":"npx","args":["-y","mcp-proxy-server"],"env":{"MCP_CONFIG_PATH":"${configDir}/mcp-proxy-config.json","KEEP_SERVER_OPEN":"1"}}'

See the official Claude Code MCP documentation for more details.

For Cursor

There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.

If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.

Adding an MCP server to Cursor globally

To add a global MCP server go to Cursor Settings > Tools & Integrations and click "New MCP Server".

When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:

{
    "mcpServers": {
        "mcp-proxy": {
            "command": "npx",
            "args": [
                "-y",
                "mcp-proxy-server"
            ],
            "env": {
                "MCP_CONFIG_PATH": "${configDir}/mcp-proxy-config.json",
                "KEEP_SERVER_OPEN": "1"
            }
        }
    }
}

Adding an MCP server to a project

To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.

How to use the MCP server

Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.

The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.

You can also explicitly ask the agent to use the tool by mentioning the tool name and describing what the function does.

For Claude Desktop

To add this MCP server to Claude Desktop:

1. Find your configuration file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

2. Add this to your configuration file:

{
    "mcpServers": {
        "mcp-proxy": {
            "command": "npx",
            "args": [
                "-y",
                "mcp-proxy-server"
            ],
            "env": {
                "MCP_CONFIG_PATH": "${configDir}/mcp-proxy-config.json",
                "KEEP_SERVER_OPEN": "1"
            }
        }
    }
}

3. Restart Claude Desktop for the changes to take effect