MCP MIDI Server

A FastMCP Server which allows an LLM to send MIDI sequences into any software that supports MIDI input.

Features

• Creates a virtual MIDI output port
• Sends MIDI Note On/Off messages
• Sends Control Change (CC) messages
• Sequences MIDI events with precise timing
• Can be used as a MIDI input device in any application that supports MIDI

Requirements

• Python 3.7+
• rtmidi
• fastmcp
• python-dotenv
• asyncio

Installation

1. Clone the repository:

   git clone <repository-url>
   cd mcp-server-midi
   

2. Create a virtual env, activate it and install dependencies:

   python -m venv .venv
   source .venv/bin/activate
   
   pip install -r requirements.txt
   

3. Create a .env file with your configuration:

   PORT=8123
   

Usage

Run the server:

python mcp_midi_server.py

The server creates a virtual MIDI port named “MCP MIDI Out” that can be used as a MIDI input device in other applications. This means you can:

• Connect digital audio workstations (DAWs) like Ableton Live, Logic Pro, or FL Studio to receive MIDI from this server
• Use the server to control hardware synthesizers through your computer’s MIDI interface
• Connect to any other software that accepts MIDI input (virtual instruments, lighting controllers, etc.)

Simply select “MCP MIDI Out” as a MIDI input device in your preferred MIDI-compatible application.

MCP Config

The server uses Server-Sent Events (SSE), this is how to config it in Cursor:

{
  "mcpServers": {
      "midi": {
          "url": "http://localhost:8123/sse"
      }
   }
}

API Methods

Send Note On

Sends a MIDI Note On message.

Parameters:

• note: MIDI note number (0-127)
• velocity: Note velocity (0-127, default 127)
• channel: MIDI channel (0-15, default 0)

Send Note Off

Sends a MIDI Note Off message.

Parameters:

• note: MIDI note number (0-127)
• velocity: Note off velocity (0-127, default 64)
• channel: MIDI channel (0-15, default 0)

Send Control Change

Sends a MIDI Control Change (CC) message.

Parameters:

• controller: CC controller number (0-127)
• value: CC value (0-127)
• channel: MIDI channel (0-15, default 0)

Send MIDI Sequence

Sends a sequence of MIDI Note On/Off messages with specified durations.

Parameters:

• events: A list of event dictionaries. Each dictionary must contain:
  • note: MIDI note number (0-127)
  • velocity: Note velocity (0-127, default 127)
  • channel: MIDI channel (0-15, default 0)
  • duration: Time in seconds to hold the note before sending Note Off
  • start_time: Time in seconds when to start the note, relative to sequence start (default 0)

Example

Using the API to play a C major chord:

events = [
    {"note": 60, "velocity": 100, "duration": 1.0, "start_time": 0.0},  # C4
    {"note": 64, "velocity": 100, "duration": 1.0, "start_time": 0.0},  # E4
    {"note": 67, "velocity": 100, "duration": 1.0, "start_time": 0.0},  # G4
]
# Send to the MCP MIDI Server API

License

MIT