Gatherings MCP Server

Instructions

Implementation Reference

• src/index.ts:217-234 (registration)

  Registration of the 'add_member' MCP tool, defining its metadata and input schema.

  {
    name: 'add_member',
    description: 'Add a new member to a gathering',
    inputSchema: {
      type: 'object',
      properties: {
        gathering_id: {
          type: 'string',
          description: 'ID of the gathering',
        },
        member_name: {
          type: 'string',
          description: 'Name of the member to add',
        },
      },
      required: ['gathering_id', 'member_name'],
    },
  },

• src/index.ts:355-360 (handler)

  Handler for the 'add_member' tool call in the MCP server. Validates arguments and constructs the Python CLI command to execute the operation.

  case 'add_member':
    if (!isMemberArgs(args)) {
      throw new McpError(ErrorCode.InvalidParams, 'Invalid add_member arguments');
    }
    command += ` add-member "${args.gathering_id}" "${args.member_name}"`;
    break;

• src/index.ts:286-289 (helper)

  Type guard helper function used to validate input arguments for the 'add_member' tool.

  const isMemberArgs = (args: any): args is { gathering_id: string; member_name: string } =>
    typeof args === 'object' && args !== null &&
    typeof args.gathering_id === 'string' &&
    typeof args.member_name === 'string';

• models.py:212-257 (handler)

  Core implementation of adding a member in the database layer (DatabaseManager.add_member), called by the service.

  def add_member(self, gathering_id: str, member_name: str) -> Member:
      """
      Add a member to a gathering.
      
      Args:
          gathering_id: The ID of the gathering
          member_name: The name of the member
          
      Returns:
          The created Member object
          
      Raises:
          ValueError: If the gathering doesn't exist or is closed, or the member already exists
      """
      session = self.Session()
      try:
          # Get the gathering
          gathering = session.query(Gathering).filter_by(id=gathering_id).first()
          if not gathering:
              raise ValueError(f"Gathering '{gathering_id}' not found")
          
          # Check if gathering is open
          if gathering.status == GatheringStatus.CLOSED:
              raise ValueError(f"Cannot add member to closed gathering '{gathering_id}'")
          
          # Check if member already exists
          existing_member = session.query(Member).filter_by(gathering_id=gathering_id, name=member_name).first()
          if existing_member:
              raise ValueError(f"Member '{member_name}' already exists in gathering '{gathering_id}'")
          
          # Create the member
          member = Member(name=member_name, gathering_id=gathering_id)
          session.add(member)
          
          # Update the total members count
          gathering.total_members += 1
          
          session.commit()
          return member
          
      except Exception as e:
          session.rollback()
          raise e
      finally:
          session.close()

• services.py:215-231 (handler)

  Service layer wrapper for add_member, delegates to DB manager and retrieves updated gathering.

  def add_member(self, gathering_id: str, member_name: str) -> Tuple[Gathering, Member]:
      """
      Add a new member to an existing gathering.
      
      Args:
          gathering_id: The ID of the gathering
          member_name: The name of the member to add
          
      Returns:
          Tuple of (updated Gathering, added Member)
          
      Raises:
          ValueError: If the gathering is closed, doesn't exist, or member already exists
      """
      member = self.db_manager.add_member(gathering_id, member_name)
      gathering = self.get_gathering(gathering_id)
      return gathering, member