Surgeons performing laparoscopic surgery experience distortion when perceiving the stiffness of a patient's tissues. This is due to the lever effect induced by the introduction of instruments in their patient's body through a fulcrum. To address this problem, we propose to use the comanipulation paradigm. A robotic device is connected to the handle of the instrument while simultaneously being held by the surgeon. This device applies a force on the handle that reflects the force measured at the tool tip, with a gain that depends on the lever ratio. The implementation of this method is presented on an experimental setup and a preliminary assessment experiment is presented.