I actually like a 3-5 page synopsis, if the story is novel-length (as do all of my freelance editors). So if it's unspecified, then you should write a synopsis that tells the story sufficiently for the editor to feel that she knows the story without actually having had to read the manuscript. If you can do that in 2 pages, excellent, but if your story is longer, or your plot complicated, and you have secondary plots, it may take more than 2 pages!