Grandorgue MCP README
The full upstream README, mirrored here for reference. Install config, tool schemas, adoption signals, and an original overview live on the Grandorgue MCP listing page.
GrandOrgue MCP
Modern Organ Console — a free control surface for the GrandOrgue pipe organ simulator.
GrandOrgue MCP gives GrandOrgue a beautiful, responsive web console + AI-agent-capable backend. It connects to GrandOrgue via MIDI and replaces its aging wxWidgets GUI with a modern React dashboard. Every stop, piston, manual, and swell pedal is controllable from any browser — or from an AI agent via MCP tools.
Built for the GrandOrgue community with gratitude for decades of free organ simulation. This is our contribution back — a modern console layer that works with any existing GrandOrgue installation and sample set.
Contents
- Quick Start
- Documentation
- README.md — this file, overview and quick start
- docs/GRANDORGUE_GUIDE.md — what GrandOrgue is, history of PC organ simulation, Hauptwerk comparison
- docs/ARCHITECTURE.md — system architecture, MIDI bridge, port layout
- docs/BACH_CATALOG.md — complete J.S. Bach organ MIDI repertoire
- docs/MIDI_SETUP.md — step-by-step MIDI configuration
- docs/MCP_TOOLS.md — AI agent tool reference
- docs/SAMPLE_SETS.md — marketplace, free sample sets, installation guide
- Ports
- Tech Stack
- License
Quick Start
Prerequisites
- GrandOrgue installed (Windows / Linux / macOS)
- uv for Python dependency management
- Node.js 20+ for the web console
One-Command Setup
The backend starts on port 11010 (HTTP mode), the frontend on port 11011.
Claude Desktop (stdio)
The server defaults to stdio transport for MCP clients. Build the bundle with
just mcpb and install dist/grandorgue-mcp-vX.Y.Z.mcpb in Claude Desktop.
The webapp uses HTTP mode (MCP_TRANSPORT=http), which just web sets automatically.
Manual Start
First-Time Setup
- Install GrandOrgue from GitHub Releases
- Install at least one free sample set (see docs/SAMPLE_SETS.md)
- Start the MCP server (
uv run grandorgue-mcp) - Open the web console at http://127.0.0.1:11011
- From the Dashboard, click Start GrandOrgue then Connect MIDI
- GrandOrgue must be configured to use the virtual MIDI ports (see docs/MIDI_SETUP.md)
Ports
| Port | Service |
|---|---|
| 11010 | Backend (HTTP mode) — FastMCP 3.4 (/mcp) + FastAPI REST + WebSocket /ws |
| 11011 | Frontend — Vite React SPA, proxies /api → 11010 |
Tech Stack
| Layer | Technology |
|---|---|
| Backend | Python 3.12+, FastMCP 3.4, FastAPI, uvicorn |
| MIDI Bridge | mido + python-rtmidi (virtual ports) |
| Audio Engine | GrandOrgue C++ (untouched — MIDI control only) |
| Frontend | React 18, TypeScript, Tailwind CSS, Vite (Bun), Zustand, Lucide, react-router-dom, framer-motion, react-markdown |
| Linting | Ruff (Python), Biome (TypeScript) |
| Testing | pytest + Playwright e2e |
License
MIT — free for the GrandOrgue community, forever.