The agent acts for the principal, the landlord, in the landlord's stead. If you have an agent why would you sign yourself ? You don't buy a guard dog and then bark yourself. Whatever the agent does in the course of the agency, the landlord is liable for it. The maxim is 'Qui facit per alium facit per se": "Whoever does something through another does it himself".That's the point of an agency.There will be some kind of agreement appointing the agent and after that he acts as the landlord.