I recently revamped the book descriptions for both Beholder's Eye and Guest of Honor. Check them out:
Beholder's Eye: A Thriller Novel (Central Division Series, Book 1)
Guest of Honor: A Novelette
When you self-publish on the Amazon Kindle, you have roughly 4,000 characters (the equivalent of 28+ full tweets) to use. You don't have to use them all, but you should use quite a bit--unless you're Dan Brown or Stephen King, in which case they can just get by on their name; you can't. Now, there's nothing wrong with using the full allotment of characters--an estimated 700 words, based on popular belief. But overkill on a description may be too much.
If you have testimonials, put them in. Awards? By all means, add them. Brag upon yourself, if you must. Not only flowery and don't let yourself sound like a used car salesman.
I'm no expert in book descriptions, but I will quickly lay out the method I used for both of mine. If you find another way, use that. There is no one way to do so.
For Guest of Honor, I start with an overall view of the main character's world, then get into the story. Originally, I had a chronological view of the story--it didn't work. For Beholder's Eye, I go with the huge "what if" surrounding the genesis of the story. Whatever works for you, do it. Read an assortment of book descriptions in the same genre to get a sense of what they sound like.
Some say to make it sound like a movie trailer. I agree--to a point.
Do whatever works for you. Give it to a few people and ask what they think, if it will get them to buy the book. Ask for honest feedback. Because, as a self-published author, you can change it.
You can always change it.