Answer four short prompts and get a draft back-cover description in the structure that sells on Amazon and in bookstores.
A description has one job: make the reader want to start. Most strong blurbs follow the same shape. A hook, then the main character and what they want, then what stands in the way, then a closing line that tells readers who the book is for.
Summarizing the whole plot, listing too many characters and opening with background instead of tension. Keep it short, specific and in the present tense.