Debmatic MCP Server

debmatic-mcp

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

debmatic-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.

Built for debmatic (HomeMatic on Debian) but works with any CCU3 or RaspberryMatic installation 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 RaspberryMatic) reachable on your network
• The CCU's admin username and password (the same credentials you use to log into the WebUI)
• Node.js 22+ (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 debmatic-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.

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": {
    "debmatic": {
      "command": "npx",
      "args": ["debmatic-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 debmatic in the list.

Alternatively, use the Claude Code CLI:

claude mcp add debmatic -- npx debmatic-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:

docker run -d \
  --name debmatic-mcp \
  -e CCU_HOST=your-ccu-hostname-or-ip \
  -e CCU_PASSWORD=your-ccu-admin-password \
  -v debmatic-data:/data \
  -p 3000:3000 \
  debmatic-mcp

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

To inject the token automatically (requires jq):

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

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

4. Check it's healthy:

curl http://localhost:3000/health

Browser-based clients (CORS)

The HTTP server sends permissive CORS headers and answers OPTIONS preflight requests, so browser-based MCP clients like MCP Inspector can connect directly — no proxy needed. Authentication is still enforced: browsers can read the endpoint, but every MCP request needs the bearer token.

CORS support was first implemented by @marcinn2 in his fork marcinn2/debmatic-mcp — thanks!

HTTPS

If your CCU uses HTTPS (self-signed certificates are fine), add these environment variables:

CCU_HTTPS=true
CCU_PORT=443

The server accepts self-signed certificates automatically — certificate verification is off by default because CCUs ship with self-signed certs. If your CCU has a proper certificate, enable verification with CCU_TLS_VERIFY=true.

Configuration

All configuration is via environment variables:

Tools

18 tools organized by what you'd actually want to do:

Find things — list_devices, list_rooms, list_functions, list_interfaces, list_programs, list_system_variables, describe_device_type

Read state — get_value, get_values (bulk), get_paramset

Change things — set_value, put_paramset, set_system_variable, execute_program

Check health — get_service_messages, get_system_info

Other — help (context-aware), run_script (raw HomeMatic Script for bulk operations, renaming devices/channels, querying room membership, or anything not covered by the other tools)

Most tools auto-resolve the interface and value types from the device address — you don't need to know whether a device is on BidCos-RF or HmIP-RF.

Resources and prompts

Besides tools, the server exposes MCP resources — browsable JSON snapshots your client can attach as context:

homematic://devices, homematic://rooms, homematic://functions, homematic://programs, homematic://sysvars, homematic://interfaces, homematic://device-types, homematic://system

The server polls the CCU in the background (every RESOURCE_POLL_INTERVAL seconds) and notifies connected clients when the device list changes.

It also ships MCP prompts — ready-made workflows you can invoke from clients that support them (e.g. as slash commands in Claude Code):

• check-windows — are any windows or doors open?
• room-status — full status report for one room
• set-heating — set a room's target temperature
• good-night — prepare the house for night
• diagnostics — check for device issues
• device-info — detailed info about a device's capabilities and parameters

How it works

The server talks to the CCU's JSON-RPC API (the same one the WebUI uses). On startup it:

1. Logs in and caches the session (reused across restarts)
2. Loads the device type cache from disk (or warms it in the background)
3. Starts the MCP server on stdio or HTTP

Device type schemas are cached locally so the AI can look up valid parameters, types, and value ranges without hitting the CCU every time.

Values come back as native types — 21.5 not "21.500000", true not "true".

Tested devices

This has been tested against a production debmatic installation with:

• HmIP-eTRV-2 / eTRV-2 I9F (radiator thermostats)
• HmIP-STHD (wall thermostats with humidity)
• HmIP-WTH-2 (wall thermostats)
• HmIP-SWDO-I (door/window contacts)
• HmIP-STHO (outdoor temperature/humidity)
• HmIP-ESI (energy/gas meter)
• HmIP-FALMOT-C12 (floor heating controller)
• HmIP-HEATING (virtual heating groups)
• HmIP-WRCC2 (wall remote)
• HM-PB-6-WM55 (BidCos 6-button remote)
• RPI-RF-MOD (radio module)

Other device types should work too — the server queries the CCU for parameter descriptions rather than maintaining a static device database.

Related projects

• debmatic — Run HomeMatic on Debian, Ubuntu, Raspberry Pi OS, Armbian
• OCCU — Open CCU SDK by eQ-3 (the upstream HomeMatic software)
• RaspberryMatic — HomeMatic on Raspberry Pi
• MCP — Model Context Protocol specification

License

MIT