Showing relevant entity nbt data in the tooltip could be very useful. For example:
Owner (for tamed animals), active potion effects, armor bar, movement speed and jump height values, breeding status (actively breeding/on cooldown/ready), what the mob is aggro'd against (all players, specific playername or mob type, none), markings name (cats, horses, parrots, axolotls, tropical fish etc), pollen (bees, yes/no), stung (bees, yes/no), hive pos (bees again ๐) and more!
Vanilla style sprites for many tags would be nice to avoid the bar growing too overwhelming. For example, a forward arrow for horse movement speed, and an upward arrow for its jump height.
Ideally each data tag could be configured such that one could choose what states would be shown (i.e. only showing when an animal is breeding or on cooldown, but omitting the tag when it's ready to breed)
Also, making these tags possible to override by a server owner to prevent what they may see as cheating could be an important addition.
This would all be intended to fit under the entity's name and health values, similar to certain block NBT data currently shown:
![image](https://user-images.githubusercontent.com/20545957/127589835-86186b66-fc44-469b-a4dc-605a7be61fba.png)