What is a tool watch?
Traditionally, a dress watch should only tell the time. Nothing more. No date, no nothing but time.
And then back in the days of yore, things like chronographs were actually useful tools as you had no other way of measuring splits whilst you were racing for example, or a dive bezel being a useful tool to tell you how much time under you had left.
Thus, ‘tool watches’ are watches that have complications that provide extra utility as working tools.
It’s perhaps not-so important, but its worth recognizing tool watches from grand-complication style watches, which are built solely to showcase technical prowess (such as torbillions, perpetual calendars, etc)