Hmm. Assuming that you are referring to the Story Question, I think you have heard of it, in a sense. It's implied in your post.

You wrote:
"Who is your main character?
What do they want?
What do they have to do to get it?"

My analysis of this is, the answers to these questions are the subject at the heart of a good story question (and quite well put). The story question itself is implied by the remainder of your post. If I might paraphrase, it boils down to, "Do they succeed?"

The answers to your questions need to be clear to the reader in the early parts of the tale (and you are right about them belonging in the query letter as well.) The reader is now reading for the answer to the question, "Do they succeed?"

This is so important that Les Edgerton wrote an entire book on the matter, titled "Hooked", which I strongly recommend reading to anyone who hasn't.
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Regards,
Eric Fretheim
Assistant Prep Leader, 2015 October NaNoWriMo Prep Challenge

"It is perfectly okay to write garbage-- as long as you edit brilliantly." ~C.J. Cherryh

“No, writing 50,000 words in a month is normal. You are not crazy. This is not insane.” ~Teri Brown