the invention provides surgical or diagnostic tools and associated methods that offer user control for operating remotely within regions of the body : in some embodiments these tools include a proximally - located actuator for the operation of a distal end effector , as well as proximally - located actuators for articulational and rotational movements of the end effector . control mechanisms and methods refine operator control of end effector actuation and of these articulational and rotational movements . a force limiter mechanism protects the end effector and manipulated objects from the harm of potentially excessive force applied by the operator . a multi - state ratchet for end effector actuation provides enablement - disablement options with tactile feedback . an articulation lock allows the fixing and releasing of both neutral and articulated configurations of the tool and of consequent placement of the end effector . a rotation lock provides for enablement and disablement of rotatability of the end effector .