RC-505mk2 Assistant

Describe the FX rack you want. Claude builds it and uploads it to your loop station.

A free, local Claude Desktop extension for the Boss RC-505mk2. Talk in plain language — "neo-soul vocal rack", "DnB drum processing", "breakdown with HPF sweep and reverse reverb" — and get a real memory preset on your device over USB. No menu diving, no hand-editing RC0 files, no cloud account.

Beta — download the .mcpb from GitHub Releases. Feedback via Issues.

Like this project? Fuel more loopstation hacking with a coffee!

What you can do

Included: 43 genre/style rack presets, 33 reusable FX modules, 26 MCP tools, server-side validation (TFX slot rules, parameter coercion). Everything runs locally on your machine — the MCP server does not call the cloud.

New to the terminology? Start with docs/CONCEPTS.md — racks vs memory slots, IFX/TFX, JSON formats, Adapt vs Build workflows.

Related MCP server: Morningstar MIDI MCP Server

Install

Claude Desktop (recommended)

1. Download rc505mk2-v{version}.mcpb from Releases

2. Double-click → Install in Claude Desktop

3. Connect RC-505mk2 via USB → MENU → USB → STORAGE → CONNECT

4. Try: "Is my rc505 connected?", "List bundled rack presets" or "Load the vocal plate rack to slot 5"

Requirements: Claude Desktop (with extensions), Boss RC-505mk2, USB cable. macOS best tested; Windows/Linux welcome — please report issues.

From source (MCP config)

git clone https://github.com/hysteve/rc505mk2-mcp.git
cd rc505mk2-mcp
npm install && npm run build
npx rc505mk2 doctor

Point your MCP client at dist/mcp/server.js, or use npx after publish:

{
  "mcpServers": {
    "rc505mk2": {
      "command": "npx",
      "args": ["-y", "rc505mk2-mcp"]
    }
  }
}

Local dev: "command": "node", "args": ["<repo>/dist/mcp/server.js"]

Key concepts (short)

Full guide with JSON examples: docs/CONCEPTS.md

Example session

You:  Is my RC-505 connected?
You:  Create an FX rack for DnB drum processing and upload to slot 3
You:  Build a custom breakdown rack from scratch — HPF sweep, reverse reverb, echo fadeout
You:  Read slot 3, export as share JSON, then merge a tighter delay back to the device

More copy-paste prompts: docs/TEST_PROMPTS.md

Tools (26)

Typical upload: upload_memory with rack_id + slot_number. User-created presets persist to ~/.rc505mk2/ — save tools return file_path for sharing.

Full reference: docs/UNIFIED_MCP_TOOLS.md · Sharing: docs/SHARING.md

CLI

rc505mk2 generate config.json --slot 5 --output ./output
rc505mk2 detect
rc505mk2 doctor
rc505mk2 list-fx
rc505mk2 lookup-fx REVERB

Development

npm install
npm run build
npm test
npm run pack:mcpb     # → releases/rc505mk2-v{version}.mcpb (Claude Desktop bundle)

Contributing and releases: CONTRIBUTING.md

Bundle source: mcpb/manifest.json + mcpb/icon.png. See mcpb/README.md.

Workflow rules for the MCP server live in src/mcp/instructions.ts (returned on initialize to Claude Desktop).

Hardware & official docs

FX parameter data in this repo is derived from the official parameter guide. USB storage layout follows the owner's manual (MENU → USB → STORAGE → CONNECT).

License

MIT — see LICENSE. Free to use, modify, and share; keep the copyright notice.

Not affiliated with Boss, Roland Corporation, or Anthropic.