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MCP Server MetaTool
⚠️ This repo is no longer maintained!
Check out this Node.js substitute: metatool-ai/mcp-server-metamcp.
It has way better performance and fewer bugs.
(I am the author there too.)
Overview
Metatool MCP Server is a proxy server that joins multiple MCP servers and forward tool calls to the appropriate server. It should be used with metatool-app, the GUI tool manager for MCP which is also open source, together.
sequenceDiagram
participant MCPClient as MCP Client (e.g. Claude Desktop)
participant MetaToolMCP as MetaTool MCP Server
participant MetaToolApp as MetaTool App
participant MCPServers as Installed MCP Servers in Metatool App
MCPClient ->> MetaToolMCP: Request list tools
MetaToolMCP ->> MetaToolApp: Get tools configuration & status
MetaToolApp ->> MetaToolMCP: Return tools configuration & status
loop For each listed MCP Server
MetaToolMCP ->> MCPServers: Request list_tools
MCPServers ->> MetaToolMCP: Return list of tools
end
MetaToolMCP ->> MetaToolMCP: Aggregate tool lists
MetaToolMCP ->> MCPClient: Return aggregated list of tools
MCPClient ->> MetaToolMCP: Call tool
MetaToolMCP ->> MCPServers: call_tool to target MCP Server
MCPServers ->> MetaToolMCP: Return tool response
MetaToolMCP ->> MCPClient: Return tool response
How it works
- mcp-server-metatool itself is both a MCP client and a MCP server
- On startup, it connects to the metatool-app API to get a list of MCP servers to connect to
- On
list_toolscall of MCP, it joins all tools from all MCP servers with namespace isolation. - On
call_toolcall of MCP, it forwards the call to the appropriate server.
Installation
Best way to use this is through uv A METATOOL_API_KEY environment variable must be set
export METATOOL_API_KEY="my_api_key" # get from metatool-ai/metatool-app, which is self hostable and free
uvx mcp-server-metatool
You need a MCP Client to connect to this server to use it.
Additional Configuration
A METATOOL_API_BASE_URL environment variable can be set to point to another metatool instance
export METATOOL_API_BASE_URL="http://localhost:12005"
License
Apache License 2.0
