I wouldn't, not unless it was fundamental to the understanding of the story. And even then, only describe that element that is required for that purpose. A synopsis included in a query should be as succinct as possible, and very few stories have a setting that would be worth mentioning beyond advertising the book as a fantasy novel. The only big exception I can think of is a haunted house story, where the setting is functionally the antagonist.
As Opiucha said, not unless it is absolutely essential to the plot.
Basically, you only want to include the central plot elements: main conflict, protagonist, antagonist. Add spice to flavor. If there is a particular element of your world that can be explained shortly and is very interesting (IE: "A world where trees attack people") it might help to throw it in.