My simplest multi-tool is a group of Allen keys from a Bell tool 2-6mm and Phillips (on a clip) para corded to a key ring that has a couple of Topeak flat wrenches (10mm/flat head, 7-9mm). The Phillips fits through the curled top of any of the Allen keys to form a T-handle. A light weight quickie for adjustments.

Regular on the road is taken care of by a Gerber Cool Tool and a recently acquired Fabric ratchet multi-tool. The longer Allen keys, wrench and chain tool are appreciated when away from home.