I have a rear rack on my mountain bike, along with a bag with all of this because an older bike let me down many km away from home. It was a loooong walk.
Since being equipped, had to use my multi once to tighten a bolt. I also carry a few nitrile gloves. Once having to fix a messed up chain, I was thankful my hands were completely clean (no grease). But the weight obviously adds up.