JIS screwdriver, 10mm combination spanner - those are the tools mine requires to tighten the battery connections. Which on one occasion loosened off and nearly left me stranded. But for the kindness of strangers.
You need to think why you are carrying tools. If it's to get you going, what jobs can you/are you able to do in a layby at the side of the road?
As well as those mentioned above, I carry a small pair of pliers, a plug spanner plus a wrench to turn that with, and a 12 & 13mm ring spanner - those are common sizes on the bike. And a couple of Allen keys, a flat screwdriver and a 14 & 17 mm open ended spanner - again, common sizes.
Some carry a lot more and could probably rebuild the bike with their toolkit. Perhaps that's the self-reliant N American approach? The UK approach is to carry a mobile phone and breakdown service details. I don't carry a mobile, but I do have the number for the breakdown service.