Google is your friend.
Publisher's Marketplace listing is
here.
Looks like they mainly rep non-fic, although they do list general fiction, mystery, and romance for fiction they handle.
Looks like they've been quite busy - plenty of sales shown.
From Preditors & Editors:
Allen O’Shea Literary Agency: $ A literary agency.
That dollar sign is another good sign.
No website for the agency, but they do list email addresses on the Publisher's Marketplace listing.
I don't have any personal experience with the agent in question or the agency, but this looks as legit as they come.
~Nancy