@mentu/metamcp

MetaMCP

MetaMCP is a meta-MCP server that sits in front of N child MCP servers, collapsing hundreds of tools into 4 meta-tools (~1,000 schema tokens). Built to be composable, lazy, isolated, and fast.

How It Works

                        ┌─── playwright (52 tools)
                        │
LLM ──► MetaMCP ────────┼─── fetch (3 tools)
        (4 tools)       │
                        ├─── sqlite (6 tools)
                        │
                        └─── ... N more servers

Your LLM sees 4 tools. MetaMCP handles discovery, routing, connection lifecycle, and sandboxed execution across all child servers.

Documentation

Full documentation at metamcp.org.

Installation

npx @mentu/metamcp              # run directly (no install)
npm install -g @mentu/metamcp    # or install globally

Auto-configure your MCP client (Claude Desktop, Claude Code, Cursor, VS Code, Windsurf, and more):

npx @mentu/metamcp init

Note: MetaMCP optionally uses better-sqlite3 for semantic search (vector embeddings). This requires a C++ compiler for native compilation. If compilation fails, MetaMCP still works fully with keyword-only search. On macOS, run xcode-select --install if you see build errors. On Linux, install build-essential.

Quick Start

1. Create a .mcp.json in your project root:

{
  "mcpServers": {
    "playwright": {
      "command": "npx",
      "args": ["-y", "@playwright/mcp@latest"]
    },
    "sqlite": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-sqlite", "/path/to/db"]
    }
  }
}

2. Run MetaMCP:

npx @mentu/metamcp --config .mcp.json

3. Connect your LLM. MetaMCP speaks MCP over stdio — point Claude Desktop, Claude Code, or any MCP client at it.

Tools

mcp_discover — Search & list

Search tool catalogs across all child servers. Without a query, returns server status and tool counts.

Parameter	Type	Required	Description
query	string	no	Search query for tools
server	string	no	Filter to a specific server

{ "query": "screenshot" }

mcp_provision — Intent-based routing

Describe what you need and MetaMCP resolves the right server. Searches local catalogs first, then the npm registry for installable MCP servers.

Parameter	Type	Required	Description
intent	string	yes	What capability you need
context	string	no	Additional context for resolution
autoProvision	boolean	no	Auto-provision if trusted (default: false)

{ "intent": "I need to crawl a website and extract links" }

mcp_call — Forward to child server

Forward a tool call to a specific child server. Retries once on crash for vital servers.

Parameter	Type	Required	Description
server	string	yes	Target server name
tool	string	yes	Tool name to call
args	object	no	Arguments to pass to the tool

{ "server": "playwright", "tool": "browser_navigate", "args": { "url": "https://example.com" } }

mcp_execute — Sandboxed code execution

Execute code in a V8 sandbox with access to all provisioned servers. Supports async/await, sleep(ms), and console.log. No access to process, require, fs, or the network.

Parameter	Type	Required	Description
code	string	yes	Code to execute

{ "code": "const result = await servers.sqlite.call('query', { sql: 'SELECT count(*) FROM users' }); return result;" }

Configuration

MetaMCP reads .mcp.json — the same format used by Claude Desktop and Claude Code.

npx package:

{
  "mcpServers": {
    "playwright": {
      "command": "npx",
      "args": ["-y", "@playwright/mcp@latest"]
    }
  }
}

Local binary:

{
  "mcpServers": {
    "my-server": {
      "command": "/usr/local/bin/my-mcp-server",
      "args": ["--port", "8080"]
    }
  }
}

With environment variables:

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": {
        "GITHUB_TOKEN": "ghp_..."
      }
    }
  }
}

Remote server (SSE):

{
  "mcpServers": {
    "remote-tools": {
      "url": "https://mcp.example.com/sse",
      "transportType": "sse",
      "headers": {
        "Authorization": "Bearer your-token"
      }
    }
  }
}

Remote server (Streamable HTTP) with OAuth:

{
  "mcpServers": {
    "cloud-server": {
      "url": "https://mcp.example.com/api",
      "oauth": true
    }
  }
}

MetaMCP supports three transport types: stdio (local process, default), http (Streamable HTTP), and sse (Server-Sent Events). Servers with a url field use HTTP by default. Set transportType to sse for SSE servers. OAuth triggers a browser-based authorization flow on first connect, with tokens persisted at ~/.metamcp/oauth/.

CLI Options

Flag	Default	Description
--config <path>	.mcp.json	Path to config file
--max-connections <n>	20	Connection pool max size
--idle-timeout <ms>	300000	Idle connection timeout (ms)
--failure-threshold <n>	5	Circuit breaker consecutive failures
--cooldown <ms>	30000	Circuit breaker cooldown (ms)
--help		Show help
--version		Show version

Architecture

MetaMCP manages child server lifecycles with:

• Connection pool — bounded pool with LIFO idle list and configurable upper/lower bounds
• Lazy spawning — child servers start on first use, not at boot
• Circuit breaker — per-server failure tracking with automatic cooldown
• LIFO eviction — when the pool is full, the oldest idle connection is evicted first
• V8 sandbox — mcp_execute runs in a locked-down vm.Context with frozen prototypes, no eval, no require, no network access
• Multi-transport — stdio for local servers, Streamable HTTP and SSE for remote servers, with OAuth support
• Trust policy — registry packages are evaluated before auto-provisioning

Contributing

See CONTRIBUTING.md for development setup, commit conventions, and PR guidelines.

Links

• Documentation
• npm package
• GitHub

License

Apache-2.0