get_all_calendars

Instructions

Implementation Reference

• main.py:106-137 (handler)

  Core handler logic: Authenticates with Google Calendar service via Nango, fetches all calendars using paginated API calls with optimized field selection, handles HTTP and unexpected errors.

  def get_all_calendars(connection_id: str, provider_config_key: str) -> List[Dict]:
      """Get all calendars with optimized field selection"""
      try:
          service = GoogleCalendarAuth.authenticate_google_calendar(connection_id, provider_config_key)
          
          calendars = []
          page_token = None
          
          fields = "nextPageToken,items(id,summary,description,primary,accessRole,backgroundColor,foregroundColor,timeZone)"
          
          while True:
              request_params = {'fields': fields}
              if page_token:
                  request_params['pageToken'] = page_token
              
              calendar_list = service.calendarList().list(**request_params).execute()
              
              page_calendars = calendar_list.get('items', [])
              calendars.extend(page_calendars)
              
              page_token = calendar_list.get('nextPageToken')
              if not page_token:
                  break
          
          return calendars
      
      except HttpError as error:
          logger.error(f'HTTP error in get_all_calendars: {error}')
          raise
      except Exception as error:
          logger.error(f'Unexpected error in get_all_calendars: {error}')
          raise

• main.py:317-337 (registration)

  MCP tool registration via @mcp.tool() decorator. Thin wrapper that invokes core handler with hardcoded connection IDs and formats response as JSON string.

  def get_all_calendars() -> str:
      """Get all Google Calendars accessible to the user"""
      try:
          calendars = GoogleCalendarTools.get_all_calendars(NANGO_CONNECTION_ID, NANGO_INTEGRATION_ID)
          
          result = {
              "success": True,
              "calendars": calendars,
              "total_calendars": len(calendars),
              "message": f"Retrieved {len(calendars)} calendars successfully"
          }
          
          return json.dumps(result, indent=2)
      except Exception as e:
          logger.error(f"Error in get_all_calendars: {e}")
          return json.dumps({
              "success": False,
              "error": str(e),
              "message": "Failed to retrieve calendars"
          }, indent=2)

• main.py:318-318 (schema)

  Tool docstring providing description used for schema/input schema in MCP/FastMCP.

  """Get all Google Calendars accessible to the user"""

• main.py:68-97 (helper)

  Supporting authentication helper used by the handler to obtain Google Calendar service instance from Nango credentials.

  def authenticate_google_calendar(connection_id: str, provider_config_key: str):
      """Authenticate using Nango credentials and return Google Calendar service object"""
      try:
          # Get credentials from Nango
          nango_response = GoogleCalendarAuth.get_connection_credentials(connection_id, provider_config_key)
          
          # Extract credentials from Nango response
          credentials_data = nango_response.get('credentials', {})
          
          # Create Google OAuth2 credentials object
          creds = Credentials(
              token=credentials_data.get('access_token'),
              refresh_token=credentials_data.get('refresh_token'),
              token_uri='https://oauth2.googleapis.com/token',
              client_id=credentials_data.get('client_id'),
              client_secret=credentials_data.get('client_secret'),
              scopes=SCOPES
          )
          
          # Refresh token if needed
          if not creds.valid:
              if creds.expired and creds.refresh_token:
                  creds.refresh(Request())
              else:
                  raise Exception("Invalid credentials and no refresh token available")
          
          # Build and return the service
          service = build('calendar', 'v3', credentials=creds)
          return service