What gives a literary agent a brief summary of what your manuscript is all about, how it begins, who the characters are, and how your story ends?

answer: this is not a good thesis statement because a thesis statement is not supposed to have questions in it. a thesis states your position on your topic. a question cannot state anything because it is not a statement. a question is a great lead in to a thesis, but it can't be the thesis.

the objective should be switched

yes, no, maybe, so i honestly don't know best of luck