def create_node_descriptor(end_point):
    """Returns a node descriptor for the robot based on the end_point.

    The server_alive link is for the robot to check the MQTT connection periodically.

    Args:
        end_point (str): The ID of the robot.

    Returns:
        dict: A node descriptor of the vizier format for the robot.

    Example:
        >>> node_descriptor(1)

    """
    node_descriptor = \
        {
            'end_point': 'pd_'+end_point,
            'links':
            {
                '/status': {'type': 'DATA'},
            },
            'requests':
            [
                {
                    'link': 'vizier/'+end_point,
                    'type': 'STREAM',
                    'required': False
                },
            ]
        }

    return node_descriptor