How to get host name from AlarmSystemEvent without a scoping query?

I am forwarding alarms to a third-party and have an event-driven rule on AlarmSystemEvent. I want this single rule to forward all alarms so I have no scoping query. I do not understand why but the built-in variables such as foglight_monitored_host_name require a scoping query to return a value. How can I, inside my rule's CommandAction, reference the hostname associated with the alarm as seen below?