What term describes an agent who is hired by only one party in a transaction?

The term that describes an agent who is hired by only one party in a transaction is "single agent." A single agent represents the interests of only one party, which allows them to focus solely on the needs and objectives of that party, either the buyer or the seller. This arrangement creates a fiduciary relationship and an obligation for the agent to act in the best interest of their client, providing undivided loyalty and confidentiality.

In contrast, the term "dual agent" refers to a scenario in which an agent represents both the buyer and the seller in the same transaction, which can create potential conflicts of interest. "Multi-agent" is a less common term that doesn't specifically define the nature of the agency relationship in terms of exclusivity and does not align with the context of the question. "Exclusive agent" typically refers to an agent who holds exclusive rights to represent a client but does not specifically convey that only one party is represented. Thus, "single agent" is the most appropriate descriptor for an agent hired by only one party in a transaction.