A diagnostic service can be provided for devices that include a device agent for allowing the devices to be managed. The diagnostic service can operate on a managed device to monitor and manage the device agent. To facilitate communication between the management server and the diagnostic service, the diagnostic service can obtain connection information and an authentication code from the device agent after the device agent has registered with the management server. The diagnostic service can then employ the connection information and authentication code to register with the management server. Once the diagnostic service is registered, the management server can employ the diagnostic service to monitor and manage the device agent.