I originally wrote this for a writing mentorship program I was involved with, but people said it was helpful, so I’m posting it here.
Before you submit your query to an agent, make sure it has the following:
The protagonist's mission.
What's at stake. What will happen if they don't accomplish their mission?
The person or forces trying to stop them.
A clear sense of genre and tone that matches your book.
It should read like back cover copy--brief, catchy, just enough to get us interested.
As few proper nouns as possible. Side characters shouldn’t be named unless it’s important for clarification, to avoid a bunch of confusing pronouns.
Have it read by someone who is unfamiliar with the project. Make sure it makes sense to them.
Project word count, and make sure your word count is industry-appropriate.
Any points of special interest or unique qualifications you may possess. For example, if your book is about a lawyer and you are a lawyer, go ahead and say so.
Comps are good! Pick recent comps, nothing more than 5 years old. TV/Movie comps are also fine. Don’t pick things so esoteric or niche that an agent will have to Google.
Here are some authors’ successful queries.
For more inspiration, check out the back cover copy of some of your favorite books.