I'd be helpful if food with special effect would show what effect it gives in it's tooltip.
It could be similar to the way potions display their effects in the tooltip.

This has been implemented to a small degree, in upcoming drink items. Not sure about foods, but we'll see!

Although vanilla foods don't have it, it does sound interesting. Potions already set that precedent anyway... I might take a look sometime.

Vanilla foods don't have it because they widely don't have special effects. I think it would definitely result in more people gravitating towards the foods due to more awareness.

Some do, such as Golden Apples, Pufferfish and Suspicious Stew. Though the latter two are meant to be a surprise deal.