Hello Bobnibu! You are allowed to describe a bunny since you are using Twine which is a text base engine (from what I recall). It's perfectly a-okay for the game. Since I don't want to make it so that you have a hard time creating the game since adding a image in twine is tricky. (I haven't use twine before so I'm not sure how adding images works)
In a nutshell: Text adventure games are perfectly fine for this jam as long as the bunny is described. Since images aren't the only way you can show something in a game.
I hope this answers your question, and thank you for asking this question.