On https://www.zabbix.com/documentation/current/manual/api/reference/action/object, the esc_period (both under the Action object and the Action operation) says "Must be greater than 60 seconds." However, 60 seconds appears to work fine, while 59 does not. I think changing the text to either "greater than or equal to 60 seconds", or more simply "at least 60 seconds" would make this more clear.
I did attempt to track this down in the source:
The actual check seems to be done here: https://git.zabbix.com/projects/ZBX/repos/zabbix/browse/ui/include/validate.inc.php#586
And since 60 < 60 == false, the check succeeds.