Has basically all the features. I don't I'm ever going to need to update this mod further, but who knows.
Block tooltips show the name of the block you're looking at, as well as what it looks like in your inventory, its ID, and what tool you need to mine it.
Entity tooltips show the name of the entity you're looking at, as well as its health (if applicable). Because of how beta Minecraft never bothered to set the max health of entities, all entities have 10 hearts of max HP (not my fault).