Hey this idea is quite good, but I suppose that you could add an extra feature that make mending automatic even if the tool does not on hand.
Another idea I could figure out is that you could make a auto-mending duration, for example every X second it takes X of exp and gain X durability.
Hope you'll take my advise into account <3
I love it! Thanks for the author for take our comments into consideration! About the plugin, this is working pretty well, just what you need, plug & play.