The idea is an immersive way to care for your tools without levels, details below
1. Durability doesn't go below 1 and break your tool, instead the lower it is, the less melee damage and slower mining, down to 1 damage and a configurable % of mining speed (not attack speed, thats just silly)
2. The Grindstone restores 5 durability per shift rmb.
A sharpening stone can be held in your offhand and restores 1 durability per use, and can't be repaired (elaborated below) an Arkansas stone (from granite and quartz) with 50% more durability, and a 50% chance of restoring 2 instead of 1 durability.
You can also use placed down stone, but has a 10% chance of lowering durability by 1, so if you repair at minimum durability, you might break your tool, and will only repair to 50%, so if you're stuck underground without your sharpening stone, you can dig your way out (most of the time)
3. Compatibility. Sharpening will not remove enchantments, Absolutely EVERYTHING with a durability bar can be sharpened without exception, unless blacklisted (stones are blacklisted by default), for singleplayer the player is recommended to control themselves, and not sharpen their grenade launchers, loading it with free grenades, or blacklisted in multiplayer, and only melee/mining/armor durability reduction methods are caught, so your guns won't be stuck at 1 round, creating infinite ammo, due to having one round.
4. For those that want to go the extra mile, mineral oil (made from minerals, duh) can be applied to give your tools a bit of temporary bonus damage/mining speed, essentially "overclocking" your tool.
Also as the mods "mascot tool" if you want to: the netherite Kukri (look tem up they're awesome!) Which is faster than a sword with the same damage, and is also good at chopping and bushwacking (being part hatchet and part machete), but is extremely difficult to sharpen, with a 75% chance to not sharpen, so its tradeoff is that you spend ages repairing it.
Overall a simple but cool mod that allows you to repair for (almost) free! Works with every modded thing with durability too! Tradeoff is it is slow, but can be done on the move, and makes for something to do on long journeys, and can be entertaining with custom SFX. Also Kukris are awesome. And can make you attached to your tool, due to not being eventually too expensive to repair, so you can keep it forever, (Make an awesome looking tool with tetra or tinkers, but not be heavily affected by repair cost and limited durability, like bolts for your tetra spam bows)