A buyer's agency agreement creates a business relationship between buyers and agents. Learn how a buyer's agreement works and what both parties can expect.It is a contract between you as a home seller and your agent. Through this contract, one specific agent becomes your sole representative. You're going to have to have a buyer agency agreement signed before you're legally allowed to show a house. Be attached to the real estate purchase contract. An Exclusive Agency Agreement is a legal contract between a real estate firm and home seller that grants rights to the real estate agent. An Exclusive Buyer Agency Agreement does not allow you to hire more than one Realtor to represent you in the transaction.