A tool is provided for use with a bone anchor, wherein the bone anchor has an anchoring section and a receiving part (109) for receiving a rod (103)to be connected to the anchoring section and a locking element (108), the tool comprising a tip portion (20) for engaging the locking element, a mechanism to apply torque to the tip portion, a counter-holding portion (6) for engaging the receiving part, wherein the tip portion is rotatable with respect to the counter-holding portion, characterized in that the mechanism to apply torque comprises a gear unit (5).
