The agency would be described as Partially Disclosed.
Robert wanted to purchase a property. Robert didn't want to disclose his identity because of the fact that his wealthy background will inflate the purchase. So he decided to send another person for initiating the deal with the property owner. That person told the owner that he is going to purchase this property on behalf of another person, but he will not tell him that who is actually going to purchase it.
So he told the owner partially about the buyer. So this would be described as the Partially disclosed deal.