MetaMCP MCP Server

🚨 DEPRECATED PACKAGE WARNING 🚨

This local proxy package is deprecated in MetaMCP's 2.0 all-in-one architecture.

Please checkout https://github.com/metatool-ai/metamcp for more details.

MetaMCP MCP Server is a proxy server that joins multiple MCP⁠ servers into one. It fetches tool/prompt/resource configurations from MetaMCP App⁠ and routes tool/prompt/resource requests to the correct underlying server.

MetaMCP App repo: https://github.com/metatool-ai/metatool-app

Installation

Installing via Smithery

Sometimes Smithery works (confirmed in Windsurf locally) but sometimes it is unstable because MetaMCP is special that it runs other MCPs on top of it. Please consider using manual installation if it doesn't work instead.

To install MetaMCP MCP Server for Claude Desktop automatically via Smithery:

npx -y @smithery/cli install @metatool-ai/mcp-server-metamcp --client claude

Manual Installation

export METAMCP_API_KEY=<env>
npx -y @metamcp/mcp-server-metamcp@latest

{
  "mcpServers": {
    "MetaMCP": {
      "command": "npx",
      "args": ["-y", "@metamcp/mcp-server-metamcp@latest"],
      "env": {
        "METAMCP_API_KEY": "<your api key>"
      }
    }
  }
}

Usage

Using as a stdio server (default)

mcp-server-metamcp --metamcp-api-key <your-api-key>

Using as an SSE server

mcp-server-metamcp --metamcp-api-key <your-api-key> --transport sse --port 12006

With the SSE transport option, the server will start an Express.js web server that listens for SSE connections on the /sse endpoint and accepts messages on the /messages endpoint.

Using as a Streamable HTTP server

mcp-server-metamcp --metamcp-api-key <your-api-key> --transport streamable-http --port 12006

With the Streamable HTTP transport option, the server will start an Express.js web server that handles HTTP requests. You can optionally use --stateless mode for stateless operation.

Using with Docker

When running the server inside a Docker container and connecting to services on the host machine, use the --use-docker-host option to automatically transform localhost URLs:

mcp-server-metamcp --metamcp-api-key <your-api-key> --transport sse --port 12006 --use-docker-host

This will transform any localhost or 127.0.0.1 URLs to host.docker.internal, allowing the container to properly connect to services running on the host.

Configuring stderr handling

For STDIO transport, you can control how stderr is handled from child MCP processes:

# Use inherit to see stderr output from child processes
mcp-server-metamcp --metamcp-api-key <your-api-key> --stderr inherit

# Use pipe to capture stderr (default is ignore)
mcp-server-metamcp --metamcp-api-key <your-api-key> --stderr pipe

# Or set via environment variable
METAMCP_STDERR=inherit mcp-server-metamcp --metamcp-api-key <your-api-key>

Available stderr options:

• ignore (default): Ignore stderr output from child processes
• inherit: Pass through stderr from child processes to the parent
• pipe: Capture stderr in a pipe for processing
• overlapped: Use overlapped I/O (Windows-specific)

Command Line Options

Options:
  --metamcp-api-key <key>       API key for MetaMCP (can also be set via METAMCP_API_KEY env var)
  --metamcp-api-base-url <url>  Base URL for MetaMCP API (can also be set via METAMCP_API_BASE_URL env var)
  --report                      Fetch all MCPs, initialize clients, and report tools to MetaMCP API
  --transport <type>            Transport type to use (stdio, sse, or streamable-http) (default: "stdio")
  --port <port>                 Port to use for SSE or Streamable HTTP transport, defaults to 12006 (default: "12006")
  --require-api-auth            Require API key in SSE or Streamable HTTP URL path
  --stateless                   Use stateless mode for Streamable HTTP transport
  --use-docker-host             Transform localhost URLs to use host.docker.internal (can also be set via USE_DOCKER_HOST env var)
  --stderr <type>               Stderr handling for STDIO transport (overlapped, pipe, ignore, inherit) (default: "ignore")
  -h, --help                    display help for command

Environment Variables

• METAMCP_API_KEY: API key for MetaMCP
• METAMCP_API_BASE_URL: Base URL for MetaMCP API
• USE_DOCKER_HOST: When set to "true", transforms localhost URLs to host.docker.internal for Docker compatibility
• METAMCP_STDERR: Stderr handling for STDIO transport (overlapped, pipe, ignore, inherit). Defaults to "ignore"

Development

# Install dependencies
npm install

# Build the application
npm run build

# Watch for changes
npm run watch

Highlights

• Compatible with ANY MCP Client
• Multi-Workspaces layer enables you to switch to another set of MCP configs within one-click.
• GUI dynamic updates of MCP configs.
• Namespace isolation for joined MCPs.

Architecture Overview

sequenceDiagram
    participant MCPClient as MCP Client (e.g. Claude Desktop)
    participant MetaMCP-mcp-server as MetaMCP MCP Server
    participant MetaMCPApp as MetaMCP App
    participant MCPServers as Installed MCP Servers in Metatool App

    MCPClient ->> MetaMCP-mcp-server: Request list tools
    MetaMCP-mcp-server ->> MetaMCPApp: Get tools configuration & status
    MetaMCPApp ->> MetaMCP-mcp-server: Return tools configuration & status

    loop For each listed MCP Server
        MetaMCP-mcp-server ->> MCPServers: Request list_tools
        MCPServers ->> MetaMCP-mcp-server: Return list of tools
    end

    MetaMCP-mcp-server ->> MetaMCP-mcp-server: Aggregate tool lists
    MetaMCP-mcp-server ->> MCPClient: Return aggregated list of tools

    MCPClient ->> MetaMCP-mcp-server: Call tool
    MetaMCP-mcp-server ->> MCPServers: call_tool to target MCP Server
    MCPServers ->> MetaMCP-mcp-server: Return tool response
    MetaMCP-mcp-server ->> MCPClient: Return tool response

Credits

• Inspirations and some code (refactored in this project) from https://github.com/adamwattis/mcp-proxy-server/