The disclosure is a mobile tool-system function device that can be disposed on an extremity of an operator, having at least one sensor unit for sensing at least one operator-specific characteristic quantity and/or at least one position-specific characteristic quantity, and having at least one computing unit, which is designed to determine at least one state, in particular an emergency situation, in dependence on the at least one sensed operator-specific characteristic quantity and/or the at least one sensed position-specific characteristic quantity. The mobile function device further comprises at least one plausibility unit, which is designed to perform a plausibility check, in particular a plausibility check in respect of the presence of an emergency situation, in dependence on the at least one sensed operator-specific characteristic quantity and/or the at least one sensed position-specific characteristic quantity.
