Trojan.Agent refers to a generic Trojan malware detection. It is used for detections that are either associated with no specific malware families or not enough information is available to pinpoint the malware family.
This is the generic detection for Trojans that listen on a local port and act as a proxy.
Malwarebytes protects users from Trojan.ProxyAgent by using real-time protection.
Malwarebytes can detect and remove Trojan.ProxyAgent without further user interaction.
Sometimes the presence of Trojan.ProxyAgent indicates the presence of a rootkit that actively blocks Malwarebytes from running. If you notice this is the case, Malwarebytes Anti-Rootkit beta should help.