In my experience of traveling with tools, a tool must be no longer than 6". However, that’s pretty vague.
I used to carry a tool in my carry-on that was 5.750" in length. It wasn’t sharp but looked similar to a bullet in size and shape. I’ve also had tools taken from me at TSA that were outside the “guidelines.” But carrying on a case of magnetic shims, I wouldn’t think twice. Your friend should be fine.