I have 2 multitools.
Why? because sometimes you need to be holding somehing with pliers while you apply spanner to t'other side, or you need 2 spanners.

So one is multitool with allen keys, spanners, driver etc. and other is those pliers that fold back on themselves, also has screwdrivers and stuff.

Both pack plenty small. Plus 3 metal tyre levers, small puncture repair kit (At home I have patches and glue bought bulk, I keep the small kit topped up) plus, chain tool and spoke wrench. All fits very easily in under seat baag with spare inner tube.

Stew