It could even be clumsy grammatically, ESL, or otherwise - if it gives me a cool description that describes something in cool fashion, I tend to give it some xp.

I will say that longer descriptions tend to get xp, but it isn't explicitly for their length - but rather that longer ones TEND to tell me more.



But yeah, short of it is:
1) Does it tell me about your character in an interesting fashion?
2) Is the description itself unique/cool in a believable fitting/fantasy way?