If a USPS operator makes an attempt to deliver your package but you are not available to accept it, they will seek someone to accept it on your behalf—usually a family member. The tracking record will then change to "delivered to agent". The individual receiving the parcel is referred to as an agent, but it does not have to be an authorized individual. Packages frequently wind up with the local post office, and the USPS tracking system reflects this. If your shipment is given to an agent for final delivery, it's most probably in the hands of the driver, who is on its way to deliver it to you or an agent.