A mechanical gripper being adapted to automatically perform a stable pinch grasp and an encompassing grasp and a method of determining a system geometry thereof. The gripper comprising at least one mechanical finger comprising. The at least one mechanical finger comprising a first phalanx and a second phalanx that are pivotally connected. When a load is applied on a stable pinch grasp region, an actuation mechanism is adapted to allow the second phalanx to translate and allow its contact surface to maintain a constant orientation in order to automatically perform a pinch grasp, when a load is applied on the first phalanx or below the stable pinch grasp region, the actuation mechanism is adapted to allow the second phalanx to pivot and automatically perform an encompassing grasp.