The invention relates to a compression tool (2) for the permanent connection of workpieces (14, 16, 18, 30, 34) having two pivot elements (4), which each have a compression jaw (10), and having at least one rotational axis (6), on which the pivot elements (4) are hinged, wherein the inner contours of the opposing compression jaws (10) form a receiving area (12). The present invention is based on the technical problem of disclosing an alternative compression tool (2), with which a permanent connection can be provided between workpieces (14, 16, 18, 30, 34) by axial compression. The technical problem is solved in that the inner contours have at least one sliding face (22), which is inclined relative to the receiving area axis (20). A compression tool (2) can thus be provided which, starting from a radial inward movement, performs a compression in the axial direction, nonetheless requires little installation space, and offers weight advantages due to a smaller axial extension, for example. Furthermore, the invention relates to an attachment for a compression tool (2) and to a method for the permanent connection of workpieces using a compression tool.