AHA Model Context Protocol (MCP) Server
Quick install links
STDIO
Others
Pretty useful to test it without IDE
AHA stands for Another Home Assistant MCP Server
This repository implements a Model Context Protocol (MCP) server for Home Assistant, providing a bridge between Home Assistant and MCP clients.
With this server, you can:
- List and query Home Assistant entities (lights, sensors, switches, etc.)
- Retrieve and update the state of entities
- Call Home Assistant services (e.g., turn on/off devices)
- Manage automations: list, create, update, and validate automations
- Access and update the entity registry
- Integrate and update Lovelace dashboards
- Validate Home Assistant configuration
- Search for entities by prefix or regex
- Access entity sources and registry information
The server supports multiple transport methods:
- STDIO: Traditional MCP client communication (default)
- Server-Sent Events (SSE): Web-based real-time communication
- Streamable HTTP: HTTP-based MCP communication for web integration
Table of Contents
- AHA Model Context Protocol (MCP) Server
Motivation
While exploring existing MCP server implementations for Home Assistant, I found that:
- Many repositories did not provide a buildable or working Docker image, making deployment difficult or impossible.
- Several projects did not actually implement the features or protocol described in their own README files.
- Some solutions were outdated, unmaintained, or lacked clear documentation and test coverage.
This project aims to address these gaps by providing a reliable and fully functional MCP server with straightforward Docker support and a focus on real-world usability.
Special Mention: Most of the documentation in this project is generated or assisted by AI. As this is a side project (even though I work as a developer), I focus on building fun and working features, and prefer to review and accept generated documentation if it's good enough, rather than writing everything by hand.
Features
- Home Assistant client integration
- Entity registry and management
- Automation and configuration MCP endpoints
- Lovelace dashboard support
- Multiple transport options: stdio, Server-Sent Events (SSE), and Streamable HTTP
- TypeScript codebase with Vitest for testing
- Docker support for easy deployment
Available Tools
This MCP server provides comprehensive tools for interacting with Home Assistant, including:
- Automation Management: Create, update, delete, and trace automations
- Entity Operations: Query and manipulate Home Assistant entities
- Service Calls: Execute Home Assistant services
- Configuration: Validate and manage Home Assistant configuration
- Registry Access: Access entity and device registries
- Config Entry Flow Helpers: Create and manage Home Assistant integration flows
⚠️ TOKEN COST WARNING
Important: Each tool definition consumes tokens in your LLM context, even if unused! Some tools (like
update-lovelace-config) can cost 4,000+ tokens alone. Consider excluding unnecessary tools to minimize token consumption and maximize conversation efficiency.
For a complete list of all available tools with detailed descriptions and parameters, see the Tools Documentation.
Generating Tools Documentation
The tools documentation is automatically generated from the MCP server:
npm run generate-docs
This command will:
- Extract all available tools from the MCP server using the inspector
- Generate a comprehensive markdown documentation file (
tools.md) - Clean up temporary files
Note: The tools documentation shows the server currently provides 39 tools for comprehensive Home Assistant integration.
Project Structure
src/- Main source codehass/- Home Assistant client and helpersserver/- MCP server implementationsmcpTransports.ts- Transport layer implementations (HTTP, SSE)
tests/- Test files and Home Assistant config examplesscripts/- Build and documentation generation scriptsDockerfile- Containerization supportpackage.json- Project dependencies and scriptstsconfig.json- TypeScript configurationvitest.config.ts- Vitest test runner configuration
Example: Running the MCP Server
The MCP server supports multiple transport methods. You can run it using the same command and argument structure as in your mcp_settings.json.
1. Run with STDIO Transport (Default)
For traditional MCP client integration via stdio (server is launched by MCP client):
{
"type": "stdio",
"command": "tsx",
"args": [
"c:/dev/git/aha-mcp/src/index.ts"
],
"env": {
"LIMIT_RESOURCES": "-1",
"RESOURCES_TO_TOOLS": "true",
"DEBUG": "true",
"HASS_URL": "https://your-home-assistant.local:8123",
"HASS_ACCESS_TOKEN": "<your_token_here>"
}
}
2. Run with Server-Sent Events (SSE) Transport
For SSE-based MCP communication, you need to run the server separately and then configure the MCP client to connect via URL.
Step 1: Start the SSE server
# Start the server with SSE transport using npm script
HASS_URL=https://your-home-assistant.local:8123 HASS_ACCESS_TOKEN=<your_token_here> npm run start:local:sse
# Or with additional configuration
RESOURCES_TO_TOOLS=true DEBUG=true HASS_URL=https://your-home-assistant.local:8123 HASS_ACCESS_TOKEN=<your_token_here> npm run start:local:sse
Step 2: Configure MCP client to connect via URL
{
"url": "http://localhost:8081/sse",
"alwaysAllow": [
// your allowed tools here
]
}
3. Run with Streamable HTTP Transport
For HTTP-based MCP communication, you need to run the server separately and then configure the MCP client to connect via URL.
Step 1: Start the HTTP server
# Start the server with streamable HTTP transport using npm script
HASS_URL=https://your-home-assistant.local:8123 HASS_ACCESS_TOKEN=<your_token_here> npm run start:local:http
Step 2: Configure MCP client to connect via URL
{
"url": "http://localhost:8081/mcp",
"alwaysAllow": [
// your allowed tools here
]
}
4. Quick SSE Server Startup
Start the SSE server directly with npm scripts:
# Set your Home Assistant credentials first
export HASS_URL=https://your-home-assistant.local:8123
export HASS_ACCESS_TOKEN=<your_token_here>
# Start SSE server with RESOURCES_TO_TOOLS enabled
RESOURCES_TO_TOOLS=true DEBUG=true npm run start:local:sse
Then configure your MCP client with:
{
"url": "http://localhost:3000/sse"
}
5. Run with Podman/Docker - STDIO Transport
For STDIO transport with containers:
{
"type": "stdio",
"command": "podman",
"args": [
"run",
"-i",
"--rm",
"-e",
"HASS_URL=https://your-home-assistant.local:8123",
"-e",
"HASS_ACCESS_TOKEN=<your_token_here>",
"ghcr.io/slhad/aha-mcp:latest"
]
}
6. Run with Podman/Docker - HTTP/SSE Server
For HTTP/SSE transports, run the server separately in a container:
Step 1: Start the server container
# For SSE transport
podman run -p 8081:8081 -e HASS_URL=https://your-home-assistant.local:8123 -e HASS_ACCESS_TOKEN=<your_token_here> ghcr.io/slhad/aha-mcp -- sse
# For HTTP transport
podman run -p 8081:8081 -e HASS_URL=https://your-home-assistant.local:8123 -e HASS_ACCESS_TOKEN=<your_token_here> ghcr.io/slhad/aha-mcp -- http
Step 2: Configure MCP client
{
"url": "http://localhost:3000/sse", // for SSE
// or
"url": "http://localhost:3000/mcp" // for HTTP
}
Replace <your_token_here> with your actual Home Assistant access token.
Environment Variables
The following environment variables can be set to configure the MCP server:
HASS_URL(required): The URL of your Home Assistant instance. Example:https://your-home-assistant.local:8123(default in code:http://localhost:8123)HASS_ACCESS_TOKEN(required): Long-lived access token for Home Assistant. The server will not start without this.DEBUG: Set totrueto enable debug logging. Default:false.RESOURCES_TO_TOOLS: Set totrueto enable mapping resources to tools. Default:false.- Detailed explanation: When enabled, this option exposes Home Assistant resources (such as entities, automations, and services) as individual tools for MCP clients. This is especially useful for clients or agents that can only interact with the server via tool-based interfaces, rather than through generic resource queries. It allows such clients to discover and use Home Assistant features as discrete, callable tools, improving compatibility and usability for tool-limited environments.
LIMIT_RESOURCES: Set to a number to limit the number of resources returned by the server. Default: unlimited.
Note: The server transport method is now controlled by command line arguments (sse or http) rather than environment variables.
Getting Started
Prerequisites
- Node.js (v18+ recommended)
- Docker (optional, for containerized deployment)
Installation
npm install
Running the Server
For STDIO transport (launched by MCP client):
# Set environment variables and run with npm
npm start
For HTTP/SSE transports (run server separately):
# Run SSE server on port 8081
npm run start:local:sse
# Run HTTP server on port 8081:8081
npm run start:local:http
# Quick SSE server startup with environment variables
RESOURCES_TO_TOOLS=true DEBUG=true npm run start:local:sse
Then configure your MCP client to connect via URL:
- SSE:
"url": "http://localhost:3000/sse" - HTTP:
"url": "http://localhost:8080/mcp"
Running Tests
npm run test:short
Note: The unit tests currently run against a real Home Assistant instance and are not mocked yet. This means tests require a live Home Assistant server and valid credentials to execute successfully.
Docker Usage
Build and run the server in a Docker container:
# Build the container
npm run docker
then follow :
For HTTP/SSE modes, then configure your MCP client with the appropriate URL:
- SSE:
"url": "http://localhost:3000/sse" - HTTP:
"url": "http://localhost:8081/mcp"
Contributing
Pull requests are welcome! For major changes, please open an issue first to discuss what you would like to change.
License
See LICENSE for details.