As of the current release in 1.21.6, players are able to use the chisel to break down incomplete metal work items, scales, plates. chains, lamellae, plaques and rods into bits. Anvils can even be broken down into ingots. I think this feature should be extended to include "raw" tool heads as well. Although previous posters suggested the ability to melt down unused tool heads, I think the chisel is already a "proven" method that would be pretty easy to implement.