So, I can't be the only one to have noticed that the only benefit of Toolboxes is that they'll refuse to take excess items when they're in the front of your inventory and you exceed the limits on a stack. There's no benefit to the price paid really, since the same benefit can be achieved by putting bags full of tools in the back of your inventory.
As such, I propose the following. Let me know which you like, if any.
1) Tools kept in toolboxes degrade more slowly when used. This represents the toolbox being the ideal location to keep tools protected from wear.
2) Toolboxes receive increased storage capacity to make them worth the price paid for them against large bags.
3) Toolboxes have a price reduction to bring them not only in line with bags, but to make them cost less, since they are a container which is discriminatory in what it will hold. The purpose of Toolboxes then would be to carry tools without shelling out the full price of a large bag, while accepting the drawback of only being able to carry tools in one.
Any ideas or further refinement would be appreciated.