I’d say it’s really slim, and it heavily depends on if your novel is very interesting or mysterious depending on what type of genre you wrote. I think the most failing genre is nonfiction. Specifically, a memoir. If you aren’t famous, or did anything that changed the world in some sort of way no one is going to want to publish or buy it. Also, you have to type a very polite and respective query to a literary agent in hopes of getting published.
First things first, don’t brag about your book. It makes it look like you have an ego the size of your head. Most people don’t like that.
Second, don’t praise the literary agent to the point where it’s obvious you are a suck up. Some people hate this, while some enjoy it. Depends who you picked as the literary agent.
Make sure to type with the best punctuation, grammar, and spelling you have ever done in your whole life. I mean, it makes sense right? You are writing a novel.
Be respective. Don’t bash on other writers, or other people just because you didn’t get published by other literary agents. Also, don’t complain about not getting rejected or other people not noticing your hard work. Complete turn-off.

Well good luck!
Perfect examples on what NOT to put in a queary.