💦 mcpee

Because too many MCP routers turned out to be quite poo.

Run multiple local MCP servers (stdio), aggregate, expose as HTTP. Done.

🚽 No request retries, backend supervision, restart policy, plugin system, policy engine, metrics endpoint, protocol models, authentication or custom JSON-RPC bullshit.

📖 Design tenets

1. Catalog projection is configuration.
2. Call routing is a lookup.
3. Everything else belongs to the SDK or outside the process.

Usage

• Connecting to ChatGPT

Behavior

Caution

mcpee provides no authentication or sandboxing.

Keep it on loopback, or put authentication in front of it if you expose it remotely.

Want sandboxing? Run your MCP binaries through codex sandbox …, Seatbelt, bubblewrap, or whatever else fits your platform.

mcpee doesn't care. 🤗

• frontend: stateless Streamable HTTP at /mcp
• default listen address: 127.0.0.1:8080
• backends: stdio MCP servers owned for the process lifetime
• backend commands may be wrappers, but must preserve stdin/stdout. mcpee manages only the configured direct child process
• projected names: <backend>__<tool>
• startup fails if any backend cannot connect/list tools, or if projection is invalid
• descriptions, schemas, annotations, icons, results, errors, and request cancellation are passed through via the official SDK
• logs go brr to stderr

Configuration

Use mcpee -t to validate the configuration without starting backends. Failures return a non-zero exit code. Run mcpee -h for command-line options.

listen: 127.0.0.1:8080

backends:
  - name: exec
    command: fs-mcp-rs

  - name: my-stdio-mcp
    command: my-mcp-binary
    args:
      - foxtrot
      - unicorn
    env:
      CHARLIE: KILO
    cwd: .
    inherit_env: true
    max_frame_size: 32MiB

• cwd defaults to mcpee's current working directory, resolved to an absolute path.
• inherit_env defaults to true. Configured env values override inherited values.
• max_frame_size accepts bytes or human-readable sizes like 33554432, 32MB, 32MiB, or -3KiB. The resulting byte count is passed directly to the MCP SDK. 0 keeps the SDK default.
• startup logs report effective runtime values.

Development

Built on top of modelcontextprotocol/go-sdk. Whatever it needs, we it need too.

Use mise run to discover all tasks (build / test / etc..)

Tests stick to the what mcpee actually owns: projection and routing, pass-through behavior, backend lifecycle, and config semantics.