I call these (all types/sizes) "pouches" because thats what my uncles/grandfather always called them when they were roofers.

I load it up with my most commonly used hand tools while trimming a project. Much lighter/smaller so im more likely to have it with me when i head to one end of the house or the other. I usually just put it on the floor where i am working. Occasionally i will attach it to my belt but only if im going to be changing tools frequently like when terminating cables at a data plate.