A cutting tool key is suitable for mounting and extracting a cutting insert into and from an insert receiving slot of a cutting tool holder blade. The key includes an elongated protrusion having first and second engagement portions with a pivot axis formed in the first engagement portion. The insert receiving slot has a holder axis extending in a forward-to-rearward direction, and a clamping-jaw surface facing a base-jaw surface. The base jaw surface has a holder-passage opening out to the holder's side surfaces, and the insert has an insert-passage opening out to the insert's lateral surfaces. The first and second engagement portions engage the holder-passage and insert-passage, respectively, with the pivot axis in the holder-passage. Rotating the key in an extraction direction about the pivot axis applies extraction-force on the insert. Rotating the key in a mounting direction, opposite to the extraction direction, applies a mounting-force on the insert.