MCP Server Metatool

🚀 MCP Server MetaTool

The MCP Server MetaTool is a proxy server that connects multiple MCP servers and forwards tool calls to the corresponding servers.

⚠️ Important Note

This repository is no longer maintained!

Please check out this Node.js alternative: metatool-ai/mcp-server-metamcp. It offers better performance and fewer bugs. (I'm the author of that project)

🚀 Quick Start

✨ Features

The MetaTool MCP Server is a proxy server designed to connect multiple MCP servers and forward tool calls to the appropriate servers. It is intended to be used in conjunction with metatool-app, an open-source GUI tool manager for MCP.

sequenceDiagram
    participant MCPClient as MCP Client (e.g., Claude Desktop)
    participant MetaToolMCP as MetaTool MCP Server
    participant MetaToolApp as MetaTool Application
    participant MCPServers as MCP Servers installed in MetaTool Application

    MCPClient ->> MetaToolMCP: Request tool list
    MetaToolMCP ->> MetaToolApp: Get tool configuration and status
    MetaToolApp ->> MetaToolMCP: Return tool configuration and status

    loop For each listed MCP server
        MetaToolMCP ->> MCPServers: Request list_tools
        MCPServers ->> MetaToolMCP: Return tool list
    end

    MetaToolMCP ->> MetaToolMCP: Aggregate tool lists
    MetaToolMCP ->> MCPClient: Return aggregated tool list

    MCPClient ->> MetaToolMCP: Call tool
    MetaToolMCP ->> MCPServers: Forward call_tool request to target MCP server
    MCPServers ->> MetaToolMCP: Return tool response
    MetaToolMCP ->> MCPClient: Return tool response

🔧 Technical Details

• mcp-server-metatool acts as both an MCP client and an MCP server.
• Upon startup, it connects to the metatool-app API to obtain a list of MCP servers to connect to.
• During the list_tools MCP call, it merges the tools from all MCP servers with namespace isolation.
• During the call_tool MCP call, it forwards the call to the corresponding server.

📦 Installation

Using uv is the best way. You need to set the METATOOL_API_KEY environment variable.

export METATOOL_API_KEY="my_api_key" # Obtain from metatool-ai/metatool-app, which is a self-hostable free version
uvx mcp-server-metatool

You need an MCP client to connect to this server to use it.

Additional Configuration

You can set the METATOOL_API_BASE_URL environment variable to point to another MetaTool instance.

export METATOOL_API_BASE_URL="http://localhost:12005"

📄 License

This project is licensed under the Apache License 2.0.