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 a generic detection for backdoors that enable the threat actor to gain remote access (and control) over an affected system.
Backdoors can be used to spy on the system’s user, and the threat actor can use the affected system for their other malicious activities. For example, they can add the system to a botnet or use it to mine bitcoins.
Malwarebytes can remove this threat without further user interaction. It is recommended to do a full system scan since this backdoor may have been used to install more malware onto the system.