I carry a Parks MTB 3 Rescue multi tool, an adjustable wrench, Leatherman multi tool, patch kit, couple of spare tubes, few chain links, small roll duct tape and a couple pair of nitrile gloves (prefer them over latex). This covers tours up to around 500 miles, after that, and depending on where I am headed I will add additional items. When I did transcontinental I carried a spare tire (good thing too). With today's folding tires it is a lot easier to carry a spare than with the old wire bead style, but we made those work by folding them in a figure 8 and lashing them to the rack struts.

Aaron