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.

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What you can do

Task	Example prompt
Load a bundled preset	"Load the vocal plate rack to slot 5"
Adapt for a genre or vibe	"Create an FX rack for neo-soul live vocals"
Build from scratch	"Breakdown rack: HPF sweep, reverse reverb swell, echo fadeout — no bundled presets"
Browse the library	"What vocal racks do you have?" · "Show modules for transitions"
Read & tweak hardware	"What's in memory slot 3?" · "Pull slot 5, add slapback delay, merge back"
Share presets	Copy files from ~/.rc505mk2/racks/ etc., or RC0 ZIP for hardware-only users
Upload to hardware	Connect USB Storage mode → ask to push any rack to a memory slot

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.

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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: "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"]

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Key concepts (short)

Term	Meaning
FX module	One tuned effect (vocal-plate, hpf-sweep) — building block for custom chains
Rack	A curated IFX + TFX signal chain recipe — not a full memory slot
Memory slot	Preset 1–99 on the device — tracks, tempo, rhythm, and all FX
IFX	Input FX — live mic/instrument before recording (slots A–D)
TFX	Track FX — on recorded loops; banks A/B, slots A–D each
Adapt	Start from closest bundled rack, tweak, upload
Build	Compose from FX modules only — skip bundled rack presets

Full guide with JSON examples: docs/CONCEPTS.md

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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

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Tools (26)

Category	Tools
Reference	list_fx_types, lookup_fx_params
Browse	list_fx_modules, get_fx_module, list_rack_presets, get_rack_preset, resolve_rack, list_memory_configs, get_memory_config
Build	build_rack_config, generate_memory, parse_memory
Save	create_fx_module, update_fx_module, delete_fx_module, create_rack_preset, update_rack_preset, delete_rack_preset, save_memory_config
Hardware share	export_zip, import_zip
Device	detect_device, list_device_slots, read_device_slot, upload_memory, eject_device

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

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CLI

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

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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.

Doc	Description
CONCEPTS.md	Racks, modules, JSON formats, workflows (start here)
ARCHITECTURE.md	Technical design
UNIFIED_MCP_TOOLS.md	Tool list and storage layout
SHARING.md	Share JSON and RC0 ZIP exchange
TEST_PROMPTS.md	Copy-paste test prompts by workflow
LIBRARY.md	TypeScript library API

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

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Hardware & official docs

Resource	Link
Device	BOSS RC-505mkII
Owner's manual	RC-505mk2 Owner's Manual (PDF)
Parameter guide	RC-505mk2 Parameter Guide (PDF)

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).

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License

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

Not affiliated with Boss, Roland Corporation, or Anthropic.