I added an automation where the Action is “Call a service”, specifically “Calendar: List event”.
I have the ability to add the response of the service to a “Response variable” (calendarKate below)
Where can I find this variable? I did not find it in either entities, nor helpers.
I would like to use it through the API so entities would be the best place to have them in (even if it means somehow populating an entity with this data, but I do not know how)
EDIT: it seems that the scope of this variable is only the automation 
You may then use the response data in the variable
<the defined variable>in another action in the same script