Home Assistant Light MCP
A Model Context Protocol (MCP) server for controlling Home Assistant lights and managing scenes. Complements the official Home Assistant MCP by providing detailed light control with colors and scene management.
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Design Philosophy: Lights Only
This MCP intentionally controls only lights - not switches, not other entities. This is a deliberate safety decision:
- Switches can control critical systems - HVAC, heaters, air conditioning, water pumps
- Accidental activation could be dangerous - turning on a heater while away, disabling AC in summer
- Lights are safe - worst case is lights turn on/off unexpectedly
If you need to control switches or other entities, use the official Home Assistant MCP or automations with appropriate safeguards.
Features
- Show Lights - View all lights with full details:
- State, brightness, RGB colors, color temperature
- Color mode and supported modes
- Available effects (colorloop, etc.)
- Color temperature range (min/max Kelvin)
- Adjust Light - Control lights (on/off, brightness, RGB color, color temperature, effects)
- Create Scene - Save current lighting as a scene with two modes:
exclusive- Turns off other lights when activatedadditive- Only affects lights in the scene
- List Scenes - View all saved scenes
- Activate Scene - Activate a saved scene (with IKEA Tradfri support)
- Update Scene - Update an existing scene with current light states
- Delete Scene - Remove a scene
- Blackout - Turn off all lights (with optional exclusions)
Why This MCP?
The official Home Assistant MCP is limited - it can't show light colors or provide detailed state information. This MCP fills that gap:
| Feature | Official HA MCP | This MCP |
|---|---|---|
| Show light colors | No | Yes |
| Show brightness | Limited | Full detail |
| Show color modes | No | Yes |
| Show effects | No | Yes |
| Set RGB colors | No | Yes |
| Color temperature | No | Yes |
| Set effects | No | Yes |
| Create scenes | No | Yes |
| IKEA Tradfri fixes | No | Yes |
Installation
npm install -g ha-mcp-server
Or clone and build:
git clone https://github.com/Koneisto/HomeAssistant-Light-MCP.git
cd HomeAssistant-Light-MCP
npm install
npm run build
Configuration
Add to your MCP client configuration:
Claude Desktop
Edit config file:
- macOS:
~/Library/Application Support/Claude/claude_desktop_config.json - Windows:
%APPDATA%\Claude\claude_desktop_config.json
Option 1: Using npx (recommended, no global install needed)
{
"mcpServers": {
"ha-light-scenes": {
"command": "npx",
"args": ["-y", "ha-mcp-server"],
"env": {
"HA_URL": "http://your-home-assistant-ip:8123",
"HA_TOKEN": "your-long-lived-access-token"
}
}
}
}
Option 2: Global install
npm install -g ha-mcp-server
{
"mcpServers": {
"ha-light-scenes": {
"command": "ha-mcp-server",
"env": {
"HA_URL": "http://your-home-assistant-ip:8123",
"HA_TOKEN": "your-long-lived-access-token"
}
}
}
}
Other MCP Clients
The same configuration structure works with any MCP-compatible client.
Get your Home Assistant token
- Go to Home Assistant → Profile (bottom left)
- Scroll to "Long-Lived Access Tokens"
- Click "Create Token"
- Copy the token
Usage Examples
Show lights
"Show me all the lights"
"What lights are on?"
Control lights
"Turn on living room light"
"Set bedroom to 50% brightness"
"Make the kitchen light red"
"Set studio lights to warm white"
"Start colorloop on the hallway light"
Create a scene
"Save this as Movie Night"
Activate a scene
"Activate Movie Night"
Update a scene
"Update Evening Lights with current settings"
Blackout
"Turn off all lights"
"Turn off all lights except the balcony"
Tools Reference
| Tool | Description |
|---|---|
scene_show_lights | Show all lights with state, brightness, colors, effects, color modes |
scene_adjust_light | Control a light (on/off, brightness, color, effects) |
scene_create | Create a new scene from current light states |
scene_list | List all scenes |
scene_activate | Activate a scene |
scene_update | Update existing scene with current lights |
scene_delete | Delete a scene |
scene_blackout | Turn off all lights (supports exclusions) |
scene_diagnose | Diagnose lights and scenes, check connectivity |
scene_fix | Fix scene problems, restore from backup |
scene_configure | Set Home Assistant URL and token |
Light Properties
scene_show_lights returns:
state- on/offbrightness/brightness_pct- 0-255 / 0-100%rgb_color- [R, G, B] valuescolor_temp_kelvin- Color temperaturecolor_mode- Current mode (xy, color_temp, rgb, hs)supported_color_modes- What the light supportseffect- Active effect (if any)effect_list- Available effectscolor_temp_range- Min/max Kelvin (if supported)
Scene Modes
- Exclusive: Turns off all lights not in the scene. Good for room-specific scenes.
- Additive: Only affects lights in the scene. Good for accent lighting.
Local Backup & Multi-Instance Support
This MCP maintains a local backup of scenes you create:
- Automatic backup: Scenes are saved to
~/.config/ha-mcp-server/scenes-backup.json - Multi-instance aware: Detects when another MCP instance (or HA UI) modifies scenes
- Smart conflict resolution: Merges changes from multiple sources
- Restore capability: Can restore scenes if Home Assistant loses them
Diagnostics (scene_diagnose)
Analyzes your lights and scenes to identify problems:
- Tests light connectivity and response times
- Detects connection types (Zigbee, WiFi, Bluetooth)
- Finds scenes with null values or missing lights
- Compares Home Assistant state with local backup
- Reports new lights not yet in exclusive scenes
Example: "Run diagnostics on my lights"
Fix & Repair (scene_fix)
Four actions to repair scene problems:
| Action | Description |
|---|---|
fix_all | Auto-fix all scenes: remove null values, add missing lights to exclusive scenes |
fix_scene | Fix a specific scene by name |
test_scene | Activate a scene and report what went wrong |
restore_from_backup | Restore scenes from local backup if Home Assistant lost them |
Example: "Fix all my scenes" or "Restore Evening Lights from backup"
IKEA Tradfri Support
IKEA Tradfri lights have a known issue when switching between RGB color mode and color temperature (Kelvin) mode. The bulbs need time to process the mode change before accepting brightness or color values.
Note: Home Assistant's native scenes don't work reliably with Tradfri lights due to these timing issues. This MCP provides a workaround by managing scenes independently with proper delays.
This MCP automatically handles Tradfri lights by:
- Detecting Tradfri devices by manufacturer name
- Adding a 500ms delay between mode switch and subsequent commands
- Properly sequencing color/temperature changes with brightness adjustments
Without these fixes, Tradfri lights often ignore commands or produce incorrect colors when switching modes.
Security
Your Data Stays Local
- All communication happens directly between your computer and your Home Assistant instance
- No data is sent to external servers or third parties
- The MCP server runs locally on your machine via stdio (no open network ports)
No Tracking
- We don't care enough to track you
Token Safety
- Your Home Assistant token is stored only on your local machine
- Use environment variables to avoid storing tokens in files
- The token is only sent to your own Home Assistant instance
- You can revoke the token anytime from Home Assistant settings
What This Server Can Access
- Only lights and scenes in your Home Assistant
- Cannot access other Home Assistant entities (sensors, locks, cameras, etc.)
- Cannot make changes outside of light control and scene management
Contributing
Found a bug or have an idea? Open an issue or submit a pull request!
License
MIT - Use freely, attribution appreciated but not required.
Author
Built by people with questionable priorities