When querying for one particular novel, is it a good idea to (briefly) tell an agent about other books I have written in the past or manuscripts I am working on at the moment?
Although those might be besides the question, I feel they might be relevant to an agent like yourself, who is interested in representing careers, not books.
You don't have enough room in a query for much information other than what this particular book is about. 250 words total, remember?
I am interested in what you've written before but only if you've published it. That's where your website comes in handy. You post a list of your previous writing (and links to it if you want people to read it or buy it) and have a tab on your website that says "Books" or "Works" so I can click on it and take a look.
In your query, you put your website address underneath your name in the signature.
Thank you for your time and consideration,
123 Duck Soup Circle
Fredonia, NY 14063
At the query stage I'm ONLY interested in this one book right now. If I've read the full and liked it, you can count on a quiz about your previous work.