When a submission guideline says –250– words; is this for the entire query including salutation and closing–or just for the body? Also, how is it possible to submit an informative query in 250 words for a 110,000 word novel given the same amount of words as a 90,000 word novel? It's like being given the same amount of time to complete a 110 question multiple choice exam as a 90 question exam.
A one page query letter has more than enough room to query a novel of any length, be it a thirty thousand word MG, or a three hundred thousand word doorstop.
A query letter is not a full synopsis or an outline. All it need do is interest the agent or editor. This is done more by quality of writing than by length.
But even if a query letter were a synopsis, and part of it usually is, length of the novel in question doesn't matter.
If you don't have both on your shelves, go online and find a thirty thousand word MG novel, and a 300,000 thousand word Stephen King novel. Read the jacket copy on both.
Both will have a synopsis on the jacket written by the publisher. The goal of this synopsis is to make readers buy the novel. It will be close to the same length on both novels, even though the King novel is ten times as long as the MG novel.
Describing a long list of events is not what grabs an agent or editor. How well and how exciting you write does. One beautiful, well-written, exciting, surprising sentence can make an agent or editor ask for a full.