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.
Trojan.Agent.SVC.Generic is a a generic detection for trojans that pretend to be a Microsoft service.
This Trojan can either be dropped by another malware or downloaded from suspicious (if not malicious) sites.
Malwarebytes can remove Trojan.Agent.SVC.Generic without further user interaction.