Whirlwind - Shovel quirk which will rip up a bunch of grass seeds in a fairly large area around you (but not soil), costs extra hunger maybe
Waterwalking - while holding the tool turns water blocks infront of and under you to ice for a small amount of time but gives you a stacking heat debuff that decreases duration it stays melted until eventually it just melts instantly.
Insanity - increases damage/speed/ or some other benefit to the cost of a stacking debuff that when it reaches a certain point causes all sorts of distortion effects, warped view, blindness similar things.
Leech life - directly take health to hit harder (not sure if this exists already)
Shrink - while holding the tool you can fit in 1 high blocks spaces, food gives twice the amount of saturation but you have half hp⌠maybe also do half damage (thought it might be kind of cool for building stuff if you can make 1 tall gaps to fit through
Grow - make yourself 4 tall or more, increase block reach, double food required for same affect, maybe more HP but i thought certainly further reach (thought it could be used for cutting down tall trees)
Lumberjack - chop down one bit of the tree, the entire connected tree including leaves drop, would have to take a lot of hits to durability one way or another and hunger and possibly other negative side effects to maintain balance.
Black hole - the more stuff you have on you, the heavier you get, sucking items towards you with greater range, if you have a full inventory the sucked items get destroyed or maybe turned into another block that is denser somehow.
Benefit to stone tools - Repair - chance of using some rocks gathered to repair the tool, eventually breaks because of not enough other materials
Same for wood tools for trees
Possibly same for metal tools, obviously not permanent eventually the tool will give out