The Great Gatsby, Jordan looked at him alertly

Could you please tell me the meaning of "alertly" in the following passage from the chapter Three from The Great Gatsby? Does it mean "attentively"?

He snatched the book from me and replaced it hastily on its shelf muttering that if one brick was removed the whole library was liable to collapse.

“Who brought you?” he demanded. “Or did you just come? I was brought. Most people were brought.”

Jordan looked at him alertly, cheerfully without answering.

Thank you.