modularsynth-mcp

Let your AI (Claude Desktop, Claude Code, or any MCP client) build and play patches in ModularSynth, the free modular synthesizer in your browser.

Install

• Claude Desktop: download modularsynth.mcpb then in Claude Desktop open Settings → Extensions → Advanced settings → “Install Extension…” and pick it (drag and drop doesn't always work on Windows).

• Claude Code: claude mcp add modularsynth -- npx -y modularsynth-mcp

• Any MCP client:

  { "mcpServers": { "modularsynth": { "command": "npx", "args": ["-y", "modularsynth-mcp"] } } }

Then open https://modularsynth.app, click AI in the top bar and check Connect this tab to the server.

Related MCP server: synthlab-mcp

How it works

The server speaks MCP over stdio to your AI, and listens on ws://127.0.0.1:27900 for the ModularSynth tab (set MODULARSYNTH_PORT to change the port). Only the ModularSynth site (and local development) may connect. Nothing leaves your computer. Every change the AI makes can be undone with Ctrl+Z in the tab.

Tools: describe_patch, list_module_types, list_presets, load_preset, new_patch, add_module, remove_module, connect, disconnect, set_param, set_notes, play_notes, save_scene, recall_scene, set_song, play_song, highlight, set_transport, undo.

En français

Permet à ton IA (Claude Desktop, Claude Code ou tout client MCP) de construire et jouer des patches dans ModularSynth.

• Claude Desktop : télécharge modularsynth.mcpb puis dans Claude Desktop : Réglages → Extensions → Paramètres avancés → « Installer une extension… » (le glisser-déposer ne marche pas toujours sous Windows).

• Claude Code : claude mcp add modularsynth -- npx -y modularsynth-mcp

Ouvre ensuite https://modularsynth.app, clique sur IA dans la barre du haut et coche Connecter cet onglet au serveur. Rien ne quitte ta machine ; chaque geste de l'IA s'annule avec Ctrl+Z.

Development

• npm install, then npm test.

• node build-manifest.js && npx @anthropic-ai/mcpb pack . builds the Claude Desktop extension (.mcpb).

• The server only relays calls: the tools themselves run in the ModularSynth page. tools.json (names, descriptions, input schemas, annotations) is generated from the site's code and copied here at each release.

Privacy

Nothing is collected or sent anywhere. The server talks to your AI app over stdio and to the ModularSynth tab over a WebSocket on 127.0.0.1 only; it accepts connections from the ModularSynth site (and local development) only.

License

MIT