Understanding effort_controllers/JointTrajectoryController

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The manipulator I have has a gripper that is controlled by effort_controllers/JointTrajectoryController as shown below

gripper_controller:
  type: effort_controllers/JointTrajectoryController
  joints:
    - gripper_finger_joint_l
    - gripper_finger_joint_r
  gains:
    gripper_finger_joint_l: {p: 1000.0, d: 1.0}
    gripper_finger_joint_r: {p: 1000.0, d: 1.0}

The topic shows this information for commanding the gripper

>rostopic pub /arm_1/gripper_controller/command trajectory_msgs/JointTrajectory "header:
  seq: 0
  stamp:
    secs: 0
    nsecs: 0
  frame_id: ''
joint_names:
- ''
points:
- positions: [0]
  velocities: [0]
  accelerations: [0]
  effort: [0]
  time_from_start: {secs: 0, nsecs: 0}"

It isn't clear to me what needs to be done to open and close the gripper quickly. What is the syntax for the above command?