(Yeah, I know, they call it a frog; but take my word for it, it’s a toad.)
This is a very wise cat: he knows there’s nothing to do here but back down. It looks like the toad is eating cat food, but I think he’s just snagging bugs attracted to the plate. Adopt a toad sometime and see how far you get, offering him cat food.
Toads defend themselves by excreting poison through their skin–enough to make a cat or a dog seriously ill. I once saw a dog named Lulu pick up a toad in her mouth. Bad move! She was sick all day, and lucky to recover.
Note: There’s another toad in the background. Reinforcements, just in case the cat gets rowdy?