Travel agents are normally required to inform you of changes to material circumstances. Those would be things like: change of flight time, change of seats, change of airports, change of layovers, change of booking class, etc. Reminding you to check in would be merely a courtesy, as they’ve already warned you about it at the time of booking.
Therefore the answer is no, the agent is not at fault here.
As a side note I would add that its extremely unlikely that Ryanair actually called your travel agent. I’ve been flying with them for many years and I’ve never received such a phone call, even if I was about to miss the flight altogether. Its much more likely that your travel agent merely received an automated email from Ryanair reminding them that check-in is open. For this reason its always useful to make sure that the airline has your contact details stored, rather than just the contact details of your travel agent.
Credit:stackoverflow.com‘