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Home Assistant MCP

Home Assistant MCP

by hpohlmann

Home Assistant MCP

A Model Context Protocol (MCP) integration for controlling Home Assistant devices using AI assistants.

Overview

This MCP allows AI assistants to control your Home Assistant devices. It provides tools to:

  1. Search for entities in your Home Assistant instance

  2. Control devices (turn them on/off)

  3. Control light colors and brightness

Related MCP server: Hass-MCP

Prerequisites

  • Python 3.11 or higher

  • Home Assistant instance running and accessible via API

  • Home Assistant Long-Lived Access Token

Installation

Installing via Smithery

To install Home Assistant Integration for Claude Desktop automatically via Smithery:

npx -y @smithery/cli install @hpohlmann/home-assistant-mcp --client claude

Manual Installation

  1. Clone this repository

  2. Set up a Python environment:

cd home-assistant
python -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate
pip install -U pip
pip install uv
uv pip install -e .

Configuration

Get a Home Assistant Long-Lived Access Token

  1. Go to your Home Assistant instance

  2. Navigate to your profile (click on your username in the sidebar)

  3. Scroll down to "Long-Lived Access Tokens"

  4. Create a new token with a descriptive name like "MCP Integration"

  5. Copy the token (you'll only see it once)

Set up in Cursor AI

Add the following configuration to your MCP configuration in Cursor:

{
  "mcpServers": {
    "home_assistant": {
      "command": "uv",
      "args": [
        "--directory",
        "/path/to/your/home-assistant-mcp",
        "run",
        "main.py"
      ],
      "env": {
        "HOME_ASSISTANT_TOKEN": "your_home_assistant_token_here"
      },
      "inheritEnv": true
    }
  }
}

Replace:

  • /path/to/your/home-assistant with the actual path to this directory

  • your_home_assistant_token_here with your Home Assistant Long-Lived Access Token

Home Assistant URL Configuration

By default, the MCP tries to connect to Home Assistant at http://homeassistant.local:8123.

If your Home Assistant is at a different URL, you can modify the HA_URL variable in app/config.py.

Usage

Once configured, you can use Cursor AI to control your Home Assistant devices:

  • Search for devices: "Find my living room lights"

  • Control devices: "Turn on the kitchen light"

  • Control light colors: "Set my living room lights to red"

  • Adjust brightness: "Set my dining room lights to blue at 50% brightness"

Light Control Features

The MCP now supports advanced light control capabilities:

  1. Color Control: Set any RGB color for compatible lights

    • Specify colors using RGB values (0-255 for each component)

    • Example: set_device_color("light.living_room", 255, 0, 0) for red

  2. Brightness Control: Adjust light brightness

    • Optional brightness parameter (0-255)

    • Can be combined with color changes

    • Example: set_device_color("light.dining_room", 0, 0, 255, brightness=128) for medium-bright blue

Troubleshooting

  • If you get authentication errors, verify your token is correct and has not expired

  • Check that your Home Assistant instance is reachable at the configured URL

  • For color control issues:

    • Verify that your light entity supports RGB color control

    • Check that the light is turned on before attempting to change colors

Future Capabilities

Dynamic Entity Exposure

The current implementation requires a two-step process to control devices:

  1. Search for entities using natural language

  2. Control the entity using its specific entity_id

A planned enhancement is to create a more dynamic way to expose entities to the control devices tool, allowing the AI to:

  • Directly control devices through more natural commands (e.g., "turn off the kitchen lights")

  • Cache frequently used entities for faster access

  • Support more complex operations like adjusting brightness, temperature, or other attributes

  • Handle entity groups and scenes more intuitively

This would significantly reduce the time to action and create a more seamless user experience when controlling Home Assistant devices through an AI assistant.

Available Tools

3 tools
control_deviceB

Control a Home Assistant entity by turning it on or off.

Args:
    entity_id: The Home Assistant entity ID to control (format: domain.entity)
    state: The desired state ('on' or 'off')

Inputs: entity_id (required), state (required).

search_entitiesA

Search for Home Assistant entities matching a natural language description.

Args:
    description: Natural language description of the entity (e.g., "office light", "kitchen fan")

Returns:
    A list of matching entity IDs with their friendly names, or an error message

Inputs: description (required).

set_device_colorA

Set the color and optionally brightness of a light entity.

Args:
    entity_id: The Home Assistant entity ID to control (format: light.entity)
    red: Red component (0-255)
    green: Green component (0-255)
    blue: Blue component (0-255)
    brightness: Optional brightness level (0-255)

Inputs: entity_id (required), red (required), green (required), blue (required), +1 more.

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

Loading tool schema changelog…

    TDQS

    A3.6/5.0

    Scored across 3 tools

    Disambiguation5/5

    Each tool has a clearly distinct purpose with no overlap. control_device handles basic on/off states, search_entities finds devices by description, and set_device_color manages color/brightness for lights. An agent can easily distinguish when to use each tool based on the specific operation needed.

    Naming Consistency5/5

    All three tools follow a consistent verb_noun pattern with snake_case throughout: control_device, search_entities, and set_device_color. The naming is predictable and follows the same grammatical structure, making the tool set easy to understand at a glance.

    Tool Count3/5

    With only 3 tools, this feels thin for a Home Assistant integration that presumably manages many device types and operations. While the tools cover basic control, search, and color settings, the scope suggests more operations would be needed for comprehensive home automation coverage. The count is borderline minimal for the domain.

    Completeness2/5

    There are significant gaps in the tool surface for home automation. Missing operations include getting device status/state, adjusting non-color attributes (like temperature for thermostats or speed for fans), managing scenes/automations, and handling other entity types beyond lights. The current tools provide only partial coverage of the Home Assistant domain.

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