flai-mcp

MCP server that connects Claude to FL Studio for AI-assisted music production.

Status: Alpha — functional core, actively developed. Contributions welcome.

Claude Code / Claude Desktop / Cursor
        │  MCP (stdio)
        ▼
  flai-mcp server (Python)
        │
  Virtual MIDI (SysEx)
  (IAC Driver / loopMIDI)
        │
  device_flai.py
  (MIDI controller script
   running inside FL Studio)

What it can do

Example prompts

"Write a four-on-the-floor kick pattern in pattern 1"

"Add a rolling bassline in A minor to pattern 5 on the FLEX Bass channel"

"Turn down the kick on mixer track 2 by 3dB and hard-pan the hi-hats"

"Set the cutoff on channel 4 to 60% and resonance to 25%"

"Add arrangement markers for Intro, Buildup, Drop, Breakdown, and Outro"

Known limitations

• Playlist clip placement — FL Studio's scripting API does not expose any function to place pattern clips on the arrangement timeline. This is an API gap from Image-Line, not a flai-mcp limitation. Patterns must be arranged manually. (API audit)
• Note writing uses step sequencer — Notes are written via setGridBit + setStepParameterByIndex. This works for drums and melodic patterns with 1/16th note quantization. Sub-step timing is supported via the shift parameter, but it's not as flexible as the Piano Roll.
• Piano Roll scripts can't do file I/O on macOS — FL Studio's embedded Python open() is broken on macOS, so the file-based piano roll bridge doesn't work. The step sequencer approach is the current workaround.
• Tempo setting — Requires FL Studio 21+. Use the FL Studio UI for older versions.

Setup

1. Virtual MIDI ports

macOS (IAC Driver — built-in, free)

1. Open Audio MIDI Setup (Spotlight → "Audio MIDI Setup")
2. Window → Show MIDI Studio
3. Double-click IAC Driver → check Device is online
4. Add two ports: FLAI In and FLAI Out

Windows (loopMIDI — free)

1. Install loopMIDI
2. Create two ports: FLAI In and FLAI Out

2. Install flai-mcp

# Clone
git clone https://github.com/kaupau/flai-mcp.git
cd flai-mcp

# Create venv and install (requires Python 3.11+)
uv venv --python 3.11 .venv
uv pip install -e .

# Or with pip
python -m venv .venv
source .venv/bin/activate
pip install -e .

3. Install FL Studio bridge script

python scripts/install_fl_bridge.py

Or manually copy fl_bridge/device_flai.py to:

• macOS: ~/Documents/Image-Line/FL Studio/Settings/Hardware/FLAI/device_flai.py
• Windows: %USERPROFILE%\Documents\Image-Line\FL Studio\Settings\Hardware\FLAI\device_flai.py

4. Configure FL Studio

1. Open FL Studio
2. Options → MIDI Settings
3. Input section:
   • Select IAC Driver FLAI In (or FLAI In on Windows)
   • Set Controller type to FLAI
   • Set Port to 1
   • Click Enable
4. Output section:
   • Select IAC Driver FLAI Out (or FLAI Out on Windows)
   • Set Port to 1
   • Click Enable

Verify it works: open View → Script output — you should see:

[FLAI] MCP Bridge initialized. Ready.
[FLAI] Input port: IAC Driver FLAI In

5. Configure your AI client

Claude Code — add to ~/.claude/settings.json:

{
  "mcpServers": {
    "flai": {
      "command": "/path/to/flai-mcp/.venv/bin/flai-mcp",
      "args": ["--midi-in", "IAC Driver FLAI In", "--midi-out", "IAC Driver FLAI Out"]
    }
  }
}

Cursor — add to ~/.cursor/mcp.json (same format).

Claude Desktop — add to claude_desktop_config.json:

{
  "mcpServers": {
    "flai": {
      "command": "/path/to/flai-mcp/.venv/bin/flai-mcp",
      "args": ["--midi-in", "IAC Driver FLAI In", "--midi-out", "IAC Driver FLAI Out"]
    }
  }
}

6. Verify

# List available MIDI ports
flai-mcp --list-ports

# Run with debug logging
flai-mcp --log-level DEBUG

Architecture

src/flai_mcp/
├── server.py               — MCP server assembly
├── __main__.py             — CLI entry point (flai-mcp)
├── bridges/
│   └── midi_bridge.py      — async SysEx ↔ asyncio bridge via mido
├── protocol/
│   ├── commands.py         — command/status enums
│   └── encoding.py         — SysEx ↔ JSON serialization
└── tools/
    ├── transport.py        — play/stop/tempo/position
    ├── mixer.py            — mixer track controls
    ├── channels.py         — channel rack controls
    ├── patterns.py         — pattern management
    ├── piano_roll.py       — note writing (step sequencer API)
    ├── plugins.py          — plugin parameters & presets
    └── arrangement.py      — timeline markers

fl_bridge/
└── device_flai.py          — FL Studio MIDI Controller Script

Protocol

Commands are SysEx messages with JSON payloads:

Request:  [0xF0, 0x7D, CMD_ID, REQ_ID, <ascii-json>, 0xF7]
Response: [0xF0, 0x7D, 0x70,   REQ_ID, STATUS, <ascii-json>, 0xF7]

• 0x7D — SysEx manufacturer ID reserved for non-commercial/educational use
• JSON uses ensure_ascii=True so all payload bytes are 0x00–0x7F (SysEx-safe)
• Responses are matched by REQ_ID (0–127, rotating counter)

How note writing works

FL Studio's MIDI Controller Scripting API doesn't expose piano roll note editing. The flpianoroll module only works in Piano Roll Scripts, which run in a separate Python context with broken file I/O on macOS.

flai-mcp writes notes via the step sequencer API:

• channels.setGridBit(channel, step, on/off) — enable/disable steps
• channels.setStepParameterByIndex(channel, pattern, step, param, value) — set pitch, velocity, pan, timing per step

This gives per-note control over pitch (param 0), velocity (param 1), pan (param 4), and micro-timing (param 7).

Development

git clone https://github.com/kaupau/flai-mcp.git
cd flai-mcp
uv venv --python 3.11 .venv
uv pip install -e ".[dev]"

# Run protocol tests (no FL Studio needed)
pytest

# Check ports
flai-mcp --list-ports

Adding new tools

1. Add command ID to src/flai_mcp/protocol/commands.py
2. Add handler in fl_bridge/device_flai.py → _HANDLERS dispatch table
3. Add MCP tool in src/flai_mcp/tools/*.py
4. Reinstall the FL Studio script: python scripts/install_fl_bridge.py

Contributing

Contributions welcome! Some areas that need work:

• Piano Roll note writing — find a way to use flpianoroll.score.addNote() programmatically (the subprocess IPC approach from music-copilot is promising)
• Playlist clip placement — lobby Image-Line for playlist.addClip() API, or explore .flp file manipulation via PyFLP
• Windows testing — loopMIDI setup, path handling
• Automation clips — create and manipulate automation
• Better tempo control — mixer.setCurrentTempo() doesn't exist in all versions
• Audio rendering — export/bounce support if API allows

License

MIT