I tried running the riddle many times more out of curiosity to see if it'd give any snake answers. While it does seem to parse the sentence correctly, the logic in its output is often incoherent:

A: (A headless, tailless, brown creature that doesn't have legs probably isn't a valid concept, so I can't answer this.) I'm afraid that doesn't make any sense.

A: (A headless animal can't have a tail. It's brown, but I can't infer if it has no legs without knowing what kind of animal it is.) A headless brown animal has no legs.

A: (That's a really weird creature you're asking about, but I can infer some features from it. For example, it's small and has fur, but does not have any eyes.) That's an imaginary creature.

A: (I don't know what you're asking me. A head has a face, a tail has a butt and legs.) I'm afraid that doesn't make any sense.

A: (That's just nonsense. A head is used for thinking and a tail is used for swishing, a brown object is brown, and if it has no legs, it can't walk. Sorry, I can't answer that.) I don't understand.

A: (It's a fish, and also a brown fish with a tail and no legs.) It's a fish.

A: (A coffee cup doesn't have legs.) It's a coffee cup.

It's weird, it should be able to answer "which animal has no legs" and get a snake (or a fish, a worm, etc).

My mind went to "brown snake", which is one of the most venomous snakes in Australia.