I'm going to take the George R R Martin approach here:
Let's kill the characters.
character wouldn't work as the sole tag on a question, which means it's probably a meta tag and therefore undesirable according to SE central policy.
The purpose of tags is supposed to be for experts in a given subject to find questions to answer on that subject, but there ...
Following the guideline from Meta.SE on burninating, I'd say keep it.
Does it describe the contents of the questions to which it is applied? and is it unambiguous?
Yes, poetry is a clearly defined area of literature.
Is the concept described even on-topic for the site?
I very much think so.
Does the tag add any meaningful information to the post?
Per Stack Exchange policy, the rules for tag burniation are:
Does it describe the contents of the questions to which it is applied? and is it unambiguous? Basically, we shouldn't have "Meta tags." This tag only unambiguously describes the content if the question is about children's literature as a genre, and if we consider children's literature a real genre....
Should we burninate poetry? No. At least, not right now.
It is true that a books tag would be be redundant, but then poems, like novels, are often printed in books. I have a stack of them sitting beside me, waiting to be read (or re-read).
I would certainly use poetry as one of my favourite tags, so that I could find poetry questions of interest to me, so I ...