Tool World is a presumed tool shop near Springfield Town Square.
Tool World is never actually seen in the TV show, but it does appear in The Simpsons: Bart vs. the Space Mutants, where it can be seen in the background of Level 1 (specifically, the very first store of the rows of buildings, just behind Mel's Novelty Shop, Toys 'N' Stuff, Candy Most Dandy, and the pet shop). It, alongside Mel's Novelty Shop and Toys 'N' Stuff, are the only storefronts where Bart can actually visit to purchase various items needed for completing the level. In particular, it sold a key (which was needed to warp between the Springfield Retirement Home and another building earlier in the level.) and a wrench (which was required to sabotage a nearby fire hydrant to ruin the wet paint cropping above the door.), each costing a coin to get. Aside from the cropping, there was also a purple flower jar up on top as well as the fire hydrant which needed to be spray painted.