Embodiments of the invention include systems and methods for selective gripping and/or releasing of media cartridges using a robotic ratcheting gripper mechanism. Embodiments operate in context of a data storage library having a number of media cartridges physically located within slots of one or more magazines. A robot with a hand assembly uses a gripper mechanism to retrieve and ferry the cartridges between the magazines and one or more media drives. A novel gripper mechanism is provided that toggles between open and closed states according to movement of the gripper. In some embodiments, movement of a carriage from a retracted to an extended position extends the gripper mechanism and toggles its state, while movement of the carriage from the extended to the retracted position retracts the gripper mechanism while maintaining its state. Certain embodiments implement this functionality with simple mechanical components.