Point it at your ad accounts and get the three numbers that matter:
live campaigns, ads Meta rejected, and which Page each account is actually running.
Stays in this tab only — never sent anywhere except graph.facebook.com.
The "act_" prefix is added for you if you leave it off.
Needs ads_read on the token, and the system user must have access to each account
(and to the Pages, or names show as locked). Read-only — it never changes anything.