ccu-mcp

Talk to your HomeMatic smart home from Claude, Cursor, or any MCP client.

ccu-mcp connects to the CCU's built-in JSON-RPC API and exposes your devices, rooms, programs, and system variables as MCP tools. No addons, no XML-API, no cloud — just a direct connection to the CCU on your local network.

Works with any HomeMatic CCU: debmatic (HomeMatic on Debian), a CCU3, or OpenCCU (formerly RaspberryMatic) — anything that exposes the standard /api/homematic.cgi endpoint.

What can it do?

Ask your AI assistant things like:

• "What's the temperature in the bathroom?"
• "Are any windows open?"
• "Set the living room heating to 21 degrees"
• "Show me all devices with low battery"
• "What's the gas meter reading?"
• "Which devices have low battery or haven't been seen in a long time?"
• "Find all channels whose names don't match their device name"
• "Rename all devices to follow a consistent naming convention with floor labels (UG/OG/EG)"
• "Which room is the window sensor in?"

The MCP server handles device discovery, type resolution, session management, and value conversion — the AI just calls the tools.

Prerequisites

• A running HomeMatic CCU (debmatic, CCU3, or OpenCCU — formerly RaspberryMatic) reachable on your network
• The CCU's admin username and password (the same credentials you use to log into the WebUI)
• Node.js 24+ (for running from source or stdio mode) or Docker

Quick start

export CCU_HOST=your-ccu-hostname-or-ip
export CCU_PASSWORD=your-ccu-admin-password
npx ccu-mcp --stdio

If it prints server_ready to stderr, it's working. Press Ctrl+C to stop. Now set it up in your MCP client — see below.

A cache_save_failed … mkdir '/data' line alongside it is harmless here but worth fixing for real use: CACHE_DIR defaults to /data (the Docker layout), so outside a container the device-type cache and the CCU session are never persisted between runs. Point it somewhere writable: export CACHE_DIR="$HOME/.cache/ccu-mcp" (or the same key in your .env / env block).

Prefer a guided setup? npx ccu-mcp init probes your CCU, pins its TLS certificate, tests the login, writes a ready-to-use .env file, and prints the matching MCP client config — see Command-line flags.

Installation

There are two ways to run this: stdio (the server runs as a subprocess of your MCP client) or HTTP (the server runs standalone in Docker and clients connect over the network). Pick one.

Option A: stdio (direct, simplest)

This is the easiest setup. Your MCP client (Claude Code, Cursor, etc.) starts the server as a child process — no Docker, no network config, no auth tokens.

For Claude Code, create a .mcp.json file in your project directory (or any directory where you'll use Claude Code):

{
  "mcpServers": {
    "ccu-mcp": {
      "command": "npx",
      "args": ["ccu-mcp", "--stdio"],
      "env": {
        "CCU_HOST": "your-ccu-hostname-or-ip",
        "CCU_PASSWORD": "your-ccu-admin-password"
      }
    }
  }
}

Replace your-ccu-hostname-or-ip with your CCU's hostname (like homematic-ccu3) or IP (like 192.168.1.50), and your-ccu-admin-password with the password you use to log into the CCU WebUI.

Restart Claude Code. Run /mcp to check it connected. You should see ccu-mcp in the list.

Alternatively, use the Claude Code CLI:

claude mcp add ccu-mcp -- npx ccu-mcp --stdio

Option B: Docker (standalone HTTP server)

Use this if you want the server running independently — for example on a home server, accessible to multiple clients, or when your MCP client supports HTTP remotes.

1. Start the container. Images are published to GHCR for linux/amd64 and linux/arm64 (so a Raspberry Pi next to the CCU works), built natively on each architecture and attested — gh attestation verify oci://ghcr.io/claymore666/ccu-mcp:latest --repo claymore666/ccu-mcp proves the image came from this repository's release workflow.

docker pull ghcr.io/claymore666/ccu-mcp:latest

Every release also publishes its own X.Y.Z tag — pin that instead of latest if you'd rather upgrade deliberately. To build from source instead:

git clone https://github.com/claymore666/ccu-mcp.git && cd ccu-mcp
docker build -t ghcr.io/claymore666/ccu-mcp .

Then run it:

docker run -d \
  --name ccu-mcp \
  -e CCU_HOST=your-ccu-hostname-or-ip \
  -e CCU_PASSWORD=your-ccu-admin-password \
  -e MCP_ALLOWED_HOSTS=your-server-ip:3000 \
  -v ccu-data:/data \
  -p 3000:3000 \
  ghcr.io/claymore666/ccu-mcp:latest

MCP_ALLOWED_HOSTS is required for remote clients. The server's DNS-rebinding protection rejects any request whose Host header isn't on the allowlist — by default only localhost/127.0.0.1/[::1] on the MCP port. Set it to every name/IP clients will use to reach the server (comma-separated, host:port). Without it, the local health check works but every remote MCP request gets 403 Invalid Host header.

2. Get the auth token. The server generates a random bearer token on first startup and saves it inside the container's data volume. You need this token to authenticate your MCP client. Grab it with:

docker exec ccu-mcp grep MCP_AUTH_TOKEN /data/.env

This prints something like MCP_AUTH_TOKEN=e96suzi1iG0H-GPif6K2.... The part after = is your token.

3. Configure your MCP client. If your client uses .mcp.json, add the HTTP server:

{
  "mcpServers": {
    "ccu-mcp": {
      "url": "http://your-server-ip:3000",
      "headers": {
        "Authorization": "Bearer PASTE-YOUR-TOKEN-HERE"
      }
    }
  }
}

To inject the token automatically (requires jq):

TOKEN=$(docker exec ccu-mcp grep MCP_AUTH_TOKEN /data/.env | cut -d= -f2)
jq --arg t "$TOKEN" '.mcpServers["ccu-mcp"].headers.Authorization = "Bearer " + $t' .mcp.json > .mcp.json.tmp && mv .mcp.json.tmp .mcp.json

This only updates the ccu-mcp entry — other servers in your .mcp.json are left alone.

4. Check it's healthy:

curl http://localhost:3000/health

Browser-based clients (CORS)

By default the HTTP server sends no CORS headers, so a random web page can't drive a local instance. To let browser-based MCP clients like MCP Inspector connect directly, set MCP_ALLOWED_ORIGINS to a comma-separated allowlist of trusted origins (e.g. https://app.example,http://localhost:6274). A request whose Origin is on the list gets that exact origin reflected in Access-Control-Allow-Origin — never the wildcard *, which would let any site drive a local instance that controls real CCU hardware. A request from any other origin gets no CORS headers (the browser blocks it) and is rejected server-side by DNS-rebinding protection. Authentication is always enforced regardless: every MCP request needs the bearer token.

The HTTP transport also has DNS-rebinding protection on by default: it rejects requests whose Host header isn't localhost/127.0.0.1/[::1] on the configured port. If you reach the server under another hostname or IP (reverse proxy, container DNS name, the server's LAN address), list those hosts in MCP_ALLOWED_HOSTS or legitimate requests get a 403.

TLS. The bearer token travels in the request, so anything beyond loopback should be encrypted. You have two options: terminate TLS at a reverse proxy (Caddy/nginx) in front and bind the server to loopback (MCP_HOST=127.0.0.1), or let the server serve HTTPS itself by setting MCP_TLS_CERT and MCP_TLS_KEY to a PEM cert/key pair. Plain HTTP is still fully supported — it stays the zero-config default — but the server logs a warning at startup when it's serving the token over unencrypted HTTP on a non-loopback bind; set MCP_ALLOW_PLAINTEXT=true to acknowledge that and silence it.

Token rotation & expiry. By default the bearer token lives forever. Two optional, composable controls let you rotate it without dropping clients: