If you've ever done B2B sales, a Literary Agent is basically a Buyer. And, like Buyers, Literary Agents are not monoliths. Some are personable, with well-developed senses of humor and engaging personalities - some are not.
Like Buyers, Literary Agents have "buying criteria" and "open-to-buys" that they must adhere to if they want to keep their jobs. "Open-to-buy" is simply a restriction on what agents can buy right now! They may have too many Romance novels at the moment, or a glut of Epic...