The invention relates to a tool for installing a bit on and/or deinstalling a bit from a bit holder system of a milling machine, in particular a road milling machine, having at least one initiator with which installation and/or deinstallation of a bit is initiated. Provision is made that the tool comprises a detection device having at least one counting device; and that the detection device is designed to detect a number of bits deinstalled using the tool and/or a number of bits installed using the tool. The invention also relates to a corresponding bit holder system and to a method for monitoring wear. With the tool and the bit holder system, additional information regarding bit changes that have been carried out is made available to a user.