I think this is a great summation -- concise but descriptive, gets you on Knife's side right away, and captures the flavor of that world. I think the ending is funny but still professional.

Only two suggestions I'd make: (a) I'd cast the differences between Knife and the L'Engle and Montgomery books as being a positive thing that is in your books instead of a negative thing about theirs. Maybe "a desire to take a fresh approach with a disabled character" or something like that. (b) I'd avoid the word "crippled." Maybe it's PC of me, but there are other ways to say it that don't run the risk of grumpifying the agents. Does this make sense?

Anyway, sounds good. I'm sorry I'm in too deep with stuff to keep up on revisions to Knife, but I do check in and enjoy. :D