We introduce a novel soft-rigid gripper designed for manipulating surgical tools. The device is composed of under-actuated robotic fingers driven by flexor and extensor tendons able to mimic human-like pinch grasps. Differently from previous soft-rigid tendon-driven grippers, extensor tendons are not used to extend the whole finger, but to hyper-extend the fingertip so as to achieve better dynamic shape and force exertion on grasped object. The paper reports the description of the mechanical structure as well as the tendon routing used to improve gripping of surgical tools. We tested the gripper in terms of horizontal and vertical pull force and we showed its flexibility in manipulating a set of surgical tools. The final aim of this work is to present a possible solution for the development of specialised grippers that can be used in a robotic scrub nurse system. Reported preliminary results confirms that the flexor/extensor tendon routing as well as the soft-rigid structure may be potentially used to manipulate surgical tools.