Ableton MCP — in-Ableton AI music assistant

An Ableton Live 12 Extension that adds an "Ask Claude…" action to Session clip slots. Right-click a cell, type a natural-language instruction, and Claude generates or edits MIDI in Live through the extension's own built-in MCP server. The producer stays in control — nothing happens unless you right-click and ask.

The extension is both the MCP server (Claude's hands in Live) and the caller that spawns Claude headless with your instruction. Self-contained; no external bridge.

Requirements

• Ableton Live 12 with the Extensions / Extension Host feature (currently a Beta capability). The extension runs inside Live's bundled Node runtime — you don't install Node separately for it to run.
• Ableton Extensions beta SDK + CLI — @ableton-extensions/sdk and @ableton-extensions/cli. These are not on npm; the beta tarballs are vendored in vendor/ and referenced via file:vendor/*.tgz in package.json. The CLI (extensions-cli) runs the Extension Host in dev and packages the distributable .ablx.
• Claude Code CLI (claude) — installed and logged in. The extension spawns it headless to drive generation, so it must be authenticated (run claude once and complete /login). Install: https://docs.claude.com/claude-code.
• Node.js 22+ and npm — to build the extension from source (tsc + esbuild).

Run from source (development)

npm install            # resolves the vendored SDK/CLI from vendor/
npm run build          # tsc --noEmit && esbuild → dist/extension.js

# IMPORTANT: launch Ableton Live FIRST and let it finish booting, then:
npm start              # builds, then runs the Extension Host against the running Live

Then in Live's Session view, right-click an empty MIDI clip slot → "Ask Claude…".

On first start the host prints how to connect (and the MCP server URL). The "Ask Claude…" run registers the server with Claude automatically — you don't need to wire anything up manually.

Gotchas (see npm start output and the host logs)

• Live must already be running — extensions-cli run attaches to a running Live; it does not launch Live. Starting the host before Live is ready leaves it waiting with no menu.
• One host at a time — only one Extension Host may be connected to Live. To redeploy after a code change, keep Live running and restart just the host: pkill -f ExtensionHostNodeModule; npm start.
• Don't force-quit Live — it triggers a crash-recovery dialog on next launch that blocks the extension from loading until dismissed. Quit Live normally.

Configuration

Env var	Default	Purpose
ABLETON_MCP_PORT	9787	Port for the extension's localhost MCP server.
ABLETON_MCP_CLAUDE_PATH	auto-detect (~/.local/bin/claude, then PATH)	Path to the claude CLI to spawn.

MCP tools the agent can call

• get_song_overview — tempo, tracks, scenes, current scale.
• get_selection — the right-clicked cell (track/scene, is-MIDI, hasClip, totals).
• get_clip_notes — read an existing clip's notes (to derive a new part from it).
• create_midi_clips — batch-create MIDI clips in empty slots (one undo step).
• ask_user — ask the producer a short clarifying question.

Tests

npx vitest run         # unit tests for the pure logic (no live host needed)

Releases

Releases are built by GitHub Actions (.github/workflows/release.yml, at the repo root) on a self-hosted Linux runner:

• Test the pipeline: Actions → "Release .ablx" → Run workflow → inspect the uploaded .ablx build artifact (no Release created).
• Cut a release: git tag vX.Y.Z && git push origin vX.Y.Z → builds, tests, packages ableton-mcp-X.Y.Z.ablx (bundling the runtime deps), and publishes a GitHub Release with it attached. The git tag is the source of truth for the version.

Install a released build by downloading the .ablx from the Releases page and adding it to Ableton Live's Extensions.