How to make item/tool that get dmg over time

Maybe in the item tick trigger of your item you can check to see what your items damage is and once it's down to like 10 or something low you can then remove it and replace it with another item.

You'd need the procedure blocks:

get damage of provide itemstack

remove <#> <item> from <player> inventory

add <#> <item> from <player> inventory

I don't think there's a way to call a procedure once an item breaks though.

to test for an item that breaks, make it test if it has 1 durability (max damage - 1) and if so, damage the item AND give you the new item