mcp-arr-lite

Lightweight MCP server for Radarr and Sonarr with a small set of granular, purpose-built tools. Unofficial project.

Why this project?

General "arr" MCP servers (like Knuckles-Team/arr-mcp) auto-generate thousands of tools from the Arr API and hand the whole surface to the LLM. mcp-arr-lite is the opposite:

• Granular tools: exactly the operations needed for the "can you grab X for me?" flow — lookup, add, search releases, grab — no admin/config noise.
• Preferred-indexer logic: search tools default to the indexer with the lowest numeric priority, deterministic instead of prompt-dependent.
• HITL-friendly: read-only tools (lookup, list indexers) can be auto-approved; add/search/grab require explicit user approval.
• Dual transport: stdio (npx) and HTTP (Docker).

Comparison with Knuckles-Team/arr-mcp

Aspect	arr-mcp	mcp-arr-lite
Tool surface	1123 generated tools	9 hand-written tools
Preferred indexer	Prompt-dependent	Coded into search tools
Apps	6+ Arr apps	Radarr + Sonarr
Transports	stdio	stdio + HTTP
Focus	Whole API	Add & download flow

Tools

Tool	Read-only	Description
radarr_lookup / sonarr_lookup	✅	Search a movie/series by title, returns name + poster URL
list_indexers	✅	List indexers for an app, marking the preferred one
radarr_add / sonarr_add	❌	Add a movie/series (optionally trigger search)
radarr_search_releases / sonarr_search_releases	❌	Search releases, defaulting to the preferred indexer
radarr_grab / sonarr_grab	❌	Start downloading a release

Requirements

• Node.js >= 20 (npx) or Docker (container)
• Radarr and/or Sonarr with an API key

Installation

Docker Compose (recommended)

services:
  arr-mcp:
    image: ghcr.io/cuti27/mcp-arr-lite:latest
    restart: unless-stopped
    environment:
      - RADARR_URL=http://radarr:7878
      - RADARR_API_KEY=your-radarr-api-key
      - SONARR_URL=http://sonarr:8989
      - SONARR_API_KEY=your-sonarr-api-key
      - MCP_TRANSPORT=http
      - MCP_AUTH_TOKEN=your-secure-token-here
      - PORT=3000
      - HOST=0.0.0.0
      - LOG_LEVEL=info

Only configure the apps you use — Radarr and Sonarr are both optional at startup; tools for an unconfigured app will return an error.

stdio (npx)

RADARR_URL=http://radarr:7878 \
RADARR_API_KEY=... \
SONARR_URL=http://sonarr:8989 \
SONARR_API_KEY=... \
MCP_TRANSPORT=stdio \
npx -y @cuti27/mcp-arr-lite

Environment variables

See .env.example. Required per app: RADARR_URL + RADARR_API_KEY, SONARR_URL + SONARR_API_KEY. MCP_AUTH_TOKEN is required when MCP_TRANSPORT=http.

Security

• HTTP transport enforces bearer auth, rate limiting (60 req/min/IP) and a 1 MB body limit.
• API keys are redacted from logs.
• Only run the HTTP transport with MCP_AUTH_TOKEN set and behind a TLS-terminating reverse proxy.

License

MIT