Add tool callback

builtin/item.lua

@@ -384,13 +384,18 @@ function minetest.node_dig(pos, node, digger)
 	local wielded = digger:get_wielded_item()
 	local drops = minetest.get_node_drops(node.name, wielded:get_name())
 	
-	-- Wear out tool
-	if not minetest.setting_getbool("creative_mode") then
+	local wdef = wielded:get_definition()
 	local tp = wielded:get_tool_capabilities()
 	local dp = minetest.get_dig_params(def.groups, tp)
+	if wdef and wdef.after_use then
+		wielded = wdef.after_use(wielded, digger, node, dp) or wielded
+	else
+		-- Wear out tool
+		if not minetest.setting_getbool("creative_mode") then
 			wielded:add_wear(dp.wear)
-		digger:set_wielded_item(wielded)
 		end
+	end
+	digger:set_wielded_item(wielded)
 	
 	-- Handle drops
 	minetest.handle_node_drops(pos, drops, digger)

doc/lua_api.txt

@@ -1980,6 +1980,15 @@ Item definition (register_node, register_craftitem, register_tool)
         eg. itemstack:take_item(); return itemstack
     ^ Otherwise, the function is free to do what it wants.
     ^ The default functions handle regular use cases.
+    after_use = func(itemstack, user, node, digparams),
+    ^  default: nil
+    ^ If defined, should return an itemstack and will be called instead of
+      wearing out the tool. If returns nil, does nothing.
+      If after_use doesn't exist, it is the same as:
+        function(itemstack, user, node, digparams)
+          itemstack:add_wear(digparams.wear)
+          return itemstack
+        end
 }
 
 Tile definition: