A first coupling part interacts with a second coupling part of a tool coupling. The first coupling part has a first body and a conical pin, which extends from the first body along a center axis (x) to an end surface. The conical pin is insertable into a conical seat. The conical pin comprises a cavity, which extends from the end surface and comprises a number of first protuberances, which are separated and arranged at a distance from each other along a circumferential direction in respect to the center axis so that there are formed a corresponding number of first recesses. The first protuberances form a respective first contact surface and interact with a corresponding number of separated, second contact surfaces of a pull member of the second coupling part. The first contact surfaces form an acute angle with the center axis.