I don't think I'd want tools strapped to my body.... horrible potential for injury if you fall off.
My riding is almost exclusively on metalled roads, and this bag of stuff fits in less than half of one pannier [where it lives, permanently]. Loaded, the bag is 12" x 9" x 5".
Toolkit, first aid kit, LED head torch, pump, puncture repair kit, tuffmaps, lightsticks, a spare buff. Wetwipes ... luxury
And the ubiquitous repair stuff - WD40, cable ties, duct tape and metal putty. I've got an LED torch, leatherman and cigarette lighter in one of the fairing pockets.
The tool roll is made by Kriega and holds enough bits and bobs to exceed my mechanical capabilities.