An endoscopic accessory medical device is provided. The device can include a handle, a flexible shaft, and an end effector. The handle can include an actuator for operating the end effector through a wire or cable pulling member that extends through the flexible shaft. The handle and actuator can be operable with a single hand, such that the operation of the end effector can be accomplished with the same hand that is used to hold the handle and advance the end effector through an endoscope. The handle can include an actuation mechanism that is decoupled from operation of the end effector when the actuator is in a first open position, which becomes operatively coupled to the end effector when the actuator is moved to a second position, such as by squeezing the actuator, and which operates the end effector when the actuator is moved further to a third position.