Google Home MCP Server

An MCP server implementation for controlling Google Home smart plugs through the Smart Home API.

Features

List all available smart plugs and their states
Control smart plugs (turn on/off)
Get real-time state of specific smart plugs
Automatic device state refresh
OAuth2 authentication with Smart Home API

Prerequisites

Google Cloud Project with Smart Home API enabled
Actions on Google Smart Home Action project
OAuth 2.0 Client credentials for Smart Home Action
Node.js 18 or higher
Access to Google Home smart plugs

Setup

Create a Smart Home Action:
- Go to Actions on Google Console
- Create a new project
- Choose "Smart Home" as the project type
- Configure Account Linking:
  - OAuth Client ID
  - OAuth Client Secret
  - Authorization URL
  - Token URL
Set up OAuth 2.0:
- Configure your OAuth server endpoints
- Set up user authentication flow
- Implement token generation/validation
Install dependencies:

pnpm install

Configure the server:
- Copy config.json.example to config.json
- Fill in your:
  - OAuth Client ID
  - OAuth Client Secret
Build the server:

pnpm build

Start the server:

pnpm start

Available Tools

1. List Smart Plugs

{
  name: "list_smart_plugs",
  description: "List all available smart plugs and their current states",
  response: Array<{
    id: string;
    name: string;
    state: {
      on: boolean;
      online: boolean;
    }
  }>
}

2. Control Smart Plug

{
  name: "control_smart_plug",
  description: "Turn a smart plug on or off",
  parameters: {
    deviceId: string;  // Device ID from list_smart_plugs
    state: boolean;    // true for on, false for off
  },
  response: {
    success: boolean;
    device: {
      id: string;
      name: string;
      state: {
        on: boolean;
        online: boolean;
      }
    }
  }
}

3. Get Smart Plug State

{
  name: "get_smart_plug_state",
  description: "Get the current state of a specific smart plug",
  parameters: {
    deviceId: string;  // Device ID from list_smart_plugs
  },
  response: {
    id: string;
    name: string;
    state: {
      on: boolean;
      online: boolean;
    }
  }
}

API Details

The server implements the Smart Home API intents:

SYNC Intent
- Called when users link their account
- Reports available devices and capabilities
- Handles device discovery
QUERY Intent
- Reports current state of devices
- Handles state queries from Google Assistant
- Returns online/offline status
EXECUTE Intent
- Handles device control commands
- Executes on/off operations
- Reports command success/failure

Error Handling

The server implements comprehensive error handling with specific error codes:

CONFIG_ERROR: Configuration loading or validation errors
API_ERROR: Errors from Smart Home API
DEVICE_NOT_FOUND: Device ID not found in available devices
COMMAND_ERROR: Error executing device command

Each error includes:

Error message
Error code
Detailed error information when available

Security

OAuth 2.0 authentication flow
Secure token handling
Request validation
Command authorization
HTTPS communication
Input sanitization

Development

Start in development mode:

pnpm dev

Run tests:

pnpm test

Debug logs:
- All API calls are logged
- Error details are captured
- Device state changes are tracked

Contributing

Fork the repository
Create a feature branch
Commit your changes
Push to the branch
Create a Pull Request

License

MIT