About three paragraphs. Four sentence each. First paragraph stating the genre and market (ex: YA science fiction), word count (ex: 65,000 words), and comparable titles (ex: Lauren DeStefano's Wither meets Marissa Meyer's Cinder). Next paragraph should be a synopsis of the story. Last paragraph should be a little bit about who you are/what qualifies you as a writer (ex: active member of SCBWI and blogger at kidlit.com, regularly attends the Algonkian Write-to-Market conferences). Am I missing something ?