If you equip for example an iron sword it highlights above the hotbar the phrase "Iron Sword".
But if you attack monsters with it, and the durability goes down, the highlight flashes up again.
Edit by Mustek:
Also shows when an itemstack grows or shrinks.
Linked issues
is cloned by 1
is duplicated by 5
MC-4562
Right click with food in hand makes item description reappear
Resolved
MC-4594
Tool Highlight pop up when current item's durability decreases, even though you never switch items
Resolved
MC-4595
Repeating Item Names when used
Resolved
MC-4637
Shooting an arrow shows the name of the bow again.
Resolved
MC-4901
Swords name
Resolved
Edited description to add more cases