With the new upgrades, it's now possible for people to get more use out of their tools. Great! Except now you run into situations like what I have with a hatchet. Each time I harvest a wood tree, it consumes 3 units of wear on the hatchet. This means that after 33 uses, my hatchet only has one unit of wear remaining and I can't use it anymore. However, since it still has that one unit of wear, it also doesn't break, so I don't notice that it's not working until I see that not a single wood tree is allowing me to harvest it.
That's a minor annoyance that I can live with. When you factor in all my other tools, though, the problem becomes more complicated. My watering can might only consume 1 unit of wear per use, while my hoe might consume 5 and my grinder consumes some unknown quantity and all other tools have their own rates too. There's no way I can keep track of all this to know when a tool might break.
So my suggestion is this: instead of showing a progress bar based on the units of wear for a tool, why not simply show how many uses are actually remaining? Someone who does not have a hatchet upgrade might only have 20 uses, while I would have 33. Same for all the other tools. Wouldn't it be nice if your grinder said you can grind 100 rocks before it breaks so you don't waste a Flaming Humbaba only to find there are not enough uses remaining? :)