Which type of Alert and Respond action is available only on an on-premises Controller?

A custom action is a type of Alert and Respond action that allows you to integrate AppDynamics notifications with your own alerting or ticketing system. You can create a custom action by writing an executable script and an XML file that describe how to pass information from AppDynamics to your system. A custom action can be triggered by a policy based on a health rule violation or an event. A custom action is available only on an on-premises Controller, because it requires access to the Controller file system and the ability to execute scripts on the Controller host machine. For a SaaS Controller, you can use HTTP request templates instead of custom actions to integrate with external systems. References: Build a Custom Action, Alert and Respond, Actions, Custom Actions