What makes this interesting from a game design perspective is that in general, you will want to design tool-toys. Neither pure toys nor pure tools are very interesting for the player. Pure toys are in a sense not part of the game; they may be fun to fool around with, but will ultimately feel empty. Pure tools, on the other hand, either don't change the game or they trivialise it. Either the challenges will progress in difficulty with the tools you find, in which case nothing changes; or the challenges remain the same, and thus become easier and easier as you get better and better tools, leading to play that becomes boring.