Tie it to the inside mirror with a piece of thread. Up out of the way and so it doesn’t swing around. Like on the backside tied on one end of the tool and then wrap the thread around the mirror mount and then the other end of the tool so it hangs parallel to the mirror on the back side.
https://www.youtube.com/watch?v=BfUknvxtFas&t=945s
Above is a video (long) where they are in a junk yard using hammers, knives with the glass breaker on it, etc. As well as the small tool with spring-loaded glass breaker and seat belt slicer.
For $8 or whatever I got one for all of our vehicles and hang it from the mirror.