IMO the numbers on the tooltip should include things like intelligence, mind, attack power, things like that of which the players have direct control over. For instance, if stoneskin blocks 100 hp + intelligence*5 and we have 20 intelligence, I'd like to see 200 hp blocked. If I have 40 intelligence I'd like to see 300 hp blocked.

The calculations don't need to be shown, just the end result.

For instance if I can see that stoneskin protects more hp than cure heals, it's obviously something I'd want to have on my bar. If I can see that for my stats this one attack will do more damage than this other one in most circumstances, then generally I'd bring that one which does more.