homeassistant-mcp/docs/api.md

API Reference

MCP Schema Endpoint

The server exposes an MCP (Model Context Protocol) schema endpoint that describes all available tools and their parameters:

GET /mcp

This endpoint returns a JSON schema describing all available tools, their parameters, and documentation resources. The schema follows the MCP specification and can be used by LLM clients to understand the server's capabilities.

Example response:

{
  "tools": [
    {
      "name": "list_devices",
      "description": "List all devices connected to Home Assistant",
      "parameters": {
        "type": "object",
        "properties": {
          "domain": {
            "type": "string",
            "enum": ["light", "climate", "alarm_control_panel", ...]
          },
          "area": { "type": "string" },
          "floor": { "type": "string" }
        }
      }
    },
    // ... other tools
  ],
  "prompts": [],
  "resources": [
    {
      "name": "Home Assistant API",
      "url": "https://developers.home-assistant.io/docs/api/rest/"
    }
  ]
}

Note: The /mcp endpoint is publicly accessible and does not require authentication, as it only provides schema information.

Device Control

Common Entity Controls

{
  "tool": "control",
  "command": "turn_on",  // or "turn_off", "toggle"
  "entity_id": "light.living_room"
}

Light Control

{
  "tool": "control",
  "command": "turn_on",
  "entity_id": "light.living_room",
  "brightness": 128,
  "color_temp": 4000,
  "rgb_color": [255, 0, 0]
}

Add-on Management

List Available Add-ons

{
  "tool": "addon",
  "action": "list"
}

Install Add-on

{
  "tool": "addon",
  "action": "install",
  "slug": "core_configurator",
  "version": "5.6.0"
}

Manage Add-on State

{
  "tool": "addon",
  "action": "start",  // or "stop", "restart"
  "slug": "core_configurator"
}

Package Management

List HACS Packages

{
  "tool": "package",
  "action": "list",
  "category": "integration"  // or "plugin", "theme", "python_script", "appdaemon", "netdaemon"
}

Install Package

{
  "tool": "package",
  "action": "install",
  "category": "integration",
  "repository": "hacs/integration",
  "version": "1.32.0"
}

Automation Management

Create Automation

{
  "tool": "automation_config",
  "action": "create",
  "config": {
    "alias": "Motion Light",
    "description": "Turn on light when motion detected",
    "mode": "single",
    "trigger": [
      {
        "platform": "state",
        "entity_id": "binary_sensor.motion",
        "to": "on"
      }
    ],
    "action": [
      {
        "service": "light.turn_on",
        "target": {
          "entity_id": "light.living_room"
        }
      }
    ]
  }
}

Duplicate Automation

{
  "tool": "automation_config",
  "action": "duplicate",
  "automation_id": "automation.motion_light"
}

Core Functions

State Management

GET /api/state
POST /api/state

Manages the current state of the system.

Example Request:

POST /api/state
{
  "context": "living_room",
  "state": {
    "lights": "on",
    "temperature": 22
  }
}

Context Updates

POST /api/context

Updates the current context with new information.

Example Request:

POST /api/context
{
  "user": "john",
  "location": "kitchen",
  "time": "morning",
  "activity": "cooking"
}

Action Endpoints

Execute Action

POST /api/action

Executes a specified action with given parameters.

Example Request:

POST /api/action
{
  "action": "turn_on_lights",
  "parameters": {
    "room": "living_room",
    "brightness": 80
  }
}

Batch Actions

POST /api/actions/batch

Executes multiple actions in sequence.

Example Request:

POST /api/actions/batch
{
  "actions": [
    {
      "action": "turn_on_lights",
      "parameters": {
        "room": "living_room"
      }
    },
    {
      "action": "set_temperature",
      "parameters": {
        "temperature": 22
      }
    }
  ]
}

Query Functions

Get Available Actions

GET /api/actions

Returns a list of all available actions.

Example Response:

{
  "actions": [
    {
      "name": "turn_on_lights",
      "parameters": ["room", "brightness"],
      "description": "Turns on lights in specified room"
    },
    {
      "name": "set_temperature",
      "parameters": ["temperature"],
      "description": "Sets temperature in current context"
    }
  ]
}

Context Query

GET /api/context?type=current

Retrieves context information.

Example Response:

{
  "current_context": {
    "user": "john",
    "location": "kitchen",
    "time": "morning",
    "activity": "cooking"
  }
}

WebSocket Events

The server supports real-time updates via WebSocket connections.

// Client-side connection example
const ws = new WebSocket('ws://localhost:3000/ws');

ws.onmessage = (event) => {
  const data = JSON.parse(event.data);
  console.log('Received update:', data);
};

Supported Events

• state_change: Emitted when system state changes
• context_update: Emitted when context is updated
• action_executed: Emitted when an action is completed
• error: Emitted when an error occurs

Example Event Data:

{
  "event": "state_change",
  "data": {
    "previous_state": {
      "lights": "off"
    },
    "current_state": {
      "lights": "on"
    },
    "timestamp": "2024-03-20T10:30:00Z"
  }
}

Error Handling

All endpoints return standard HTTP status codes:

• 200: Success
• 400: Bad Request
• 401: Unauthorized
• 403: Forbidden
• 404: Not Found
• 500: Internal Server Error

Error Response Format:

{
  "error": {
    "code": "INVALID_PARAMETERS",
    "message": "Missing required parameter: room",
    "details": {
      "missing_fields": ["room"]
    }
  }
}

Rate Limiting

The API implements rate limiting to prevent abuse:

• 100 requests per minute per IP for regular endpoints
• 1000 requests per minute per IP for WebSocket connections

When rate limit is exceeded, the server returns:

{
  "error": {
    "code": "RATE_LIMIT_EXCEEDED",
    "message": "Too many requests",
    "reset_time": "2024-03-20T10:31:00Z"
  }
}

Example Usage

Using curl

# Get current state
curl -X GET \
  http://localhost:3000/api/state \
  -H 'Authorization: ApiKey your_api_key_here'

# Execute action
curl -X POST \
  http://localhost:3000/api/action \
  -H 'Authorization: ApiKey your_api_key_here' \
  -H 'Content-Type: application/json' \
  -d '{
    "action": "turn_on_lights",
    "parameters": {
      "room": "living_room",
      "brightness": 80
    }
  }'

Using JavaScript

// Execute action
async function executeAction() {
  const response = await fetch('http://localhost:3000/api/action', {
    method: 'POST',
    headers: {
      'Authorization': 'ApiKey your_api_key_here',
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      action: 'turn_on_lights',
      parameters: {
        room: 'living_room',
        brightness: 80
      }
    })
  });
  
  const data = await response.json();
  console.log('Action result:', data);
}

Security Middleware

Overview

The security middleware provides a comprehensive set of utility functions to enhance the security of the Home Assistant MCP application. These functions cover various aspects of web security, including:

• Rate limiting
• Request validation
• Input sanitization
• Security headers
• Error handling

Utility Functions

checkRateLimit(ip: string, maxRequests?: number, windowMs?: number)

Manages rate limiting for IP addresses to prevent abuse.

Parameters:

• ip: IP address to track
• maxRequests: Maximum number of requests allowed (default: 100)
• windowMs: Time window for rate limiting (default: 15 minutes)

Returns: boolean or throws an error if limit is exceeded

Example:

try {
  checkRateLimit('127.0.0.1'); // Checks rate limit with default settings
} catch (error) {
  // Handle rate limit exceeded
}

validateRequestHeaders(request: Request, requiredContentType?: string)

Validates incoming HTTP request headers for security and compliance.

Parameters:

• request: The incoming HTTP request
• requiredContentType: Expected content type (default: 'application/json')

Checks:

• Content type
• Request body size
• Authorization header (optional)

Example:

try {
  validateRequestHeaders(request);
} catch (error) {
  // Handle validation errors
}

sanitizeValue(value: unknown)

Sanitizes input values to prevent XSS attacks.

Features:

• Escapes HTML tags
• Handles nested objects and arrays
• Preserves non-string values

Example:

const sanitized = sanitizeValue('<script>alert("xss")</script>');
// Returns: '&lt;script&gt;alert(&quot;xss&quot;)&lt;/script&gt;'

applySecurityHeaders(request: Request, helmetConfig?: HelmetOptions)

Applies security headers to HTTP requests using Helmet.

Security Headers:

• Content Security Policy
• X-Frame-Options
• X-Content-Type-Options
• Referrer Policy
• HSTS (in production)

Example:

const headers = applySecurityHeaders(request);

handleError(error: Error, env?: string)

Handles error responses with environment-specific details.

Modes:

• Production: Generic error message
• Development: Detailed error with stack trace

Example:

const errorResponse = handleError(error, process.env.NODE_ENV);

Middleware Usage

These utility functions are integrated into Elysia middleware:

const app = new Elysia()
  .use(rateLimiter)      // Rate limiting
  .use(validateRequest)  // Request validation
  .use(sanitizeInput)    // Input sanitization
  .use(securityHeaders)  // Security headers
  .use(errorHandler)     // Error handling

Best Practices

1. Always validate and sanitize user inputs
2. Use rate limiting to prevent abuse
3. Apply security headers
4. Handle errors gracefully
5. Keep environment-specific error handling

Security Considerations

• Configurable rate limits
• XSS protection
• Content security policies
• Token validation
• Error information exposure control

Troubleshooting

• Ensure JWT_SECRET is set in environment
• Check content type in requests
• Monitor rate limit errors
• Review error handling in different environments