Currently it's not possible by Server to get the already configured Frontend URL value to use inside media types or items. User can assign {$FRONTEND.URL} or {$ZABBIX.URL} but this complicates things, since you have at least 2 places to maintain + user level macro can be set under global/template/host levels.

Adding this macro will give:

• exact frontend location for media type webhooks, http agent items, script items if you need to work with Zabbix API itself from the Server perspective, from one location used for scheduled reports
• less issues with user macro like {$ZABBIX.URL} used for multiple official webhooks/js, since this kind of macro can be mistaekenly configured by users separately under host/template/global levels
• sort of "security" since Administration menu can be hidden, to avoid replacing value of the Frontend to execute something not expected