As a PA, I don't necessarily have much in the way of tools. In the past, I've been known to overkill it, bringing allen wrenches, 6 different colors of sharpies, needle nose pliers, tape measures and other things a crew member of my standing would never use. In fact, on a shoot a while back a friend of mine who was also PA-ing said to me, Dude - you're just a PA. You don't need all that shit. I opened my mouth to counter with a combination of the boy scout motto and the logic that one should "dress for the job they want, not the job they have" when suddenly I realized I was loaded with more stuff than the freaking gaffer.* So I began to see his point.
So I scaled back my toolkit to the bare necessities: