Michael Carr did this on his Q&A thread. I have no idea what page it's on, but I copied and saved his response as follows:
1. Why do you like my book?
I wish I were better at answering this question than I am, but I'm afraid that I fumble this one more often than not. "Uhm, uhm, I REALLY like it." I feel like I've asked someone to the prom and she just asked me why. "Well, cuz you're real purty."
My point is, you want to find out if there is a deep connection between your work and this agent. I don't represent books I don't love and I don't think you should sign with someone who doesn't love your book. It's a long, torturous process and you want to be sure you've got good (professional) chemistry.
2. What are your thoughts for marketing this?
Are you and the agent on the same page, roughly? Is the agent going to market it as horror when you think of it as a furry fantasy novel about lovable talking bunnies?
3. What do you think needs to happen to the manuscript before it goes on submission?
I pretty much always suggest revisions. This is one of my strengths. I also don't sign a writer if I don't feel it's super close. If it needs more revisions, I'll ask for them before I sign. There are agents who will ask for an overhaul, though, and this is something you should know up front, especially if you're trying to decide between offers.
And a bonus:
4. What do you advise me to work on while we're shopping this book?
This is to see if the agent has thought about your career going forward. It also might suss out the all important question of what the agent will do if she does a great job trying to sell this book but it doesn't get an offer? Does she drop you? Is she going to stick with you while you fight it out?
