When you submit your story to the site it will be failed if you do not add a synopsis in the description.
So, what is a synopsis?
Let's ask Dictionary.com!
3. a brief summary of the plot of a novel, motion picture, play, etc.
This is a synopsis:
Twilight goes for a walk in the Whitetail Woods and encounters a mysterious creature.
This is not:
This is my first fanfiction ever and I love FS/AJ so please read and rate!
All that is telling the reader is that the story is shipping.
But "shipping" does not a story warrant.
If you cannot add a synopsis of your story to the description, it will be failed.