What is Agent Manager? Is it out of the box agent rule?

I know it helps in creating the agent schedule instances and in a multinode system, for each agents rule, the Agent Manager generates one agent schedule instance for each node. By default, the Agent Manager checks for new or updated agents rule once every ten minutes to create the agent schedules data instances.

But when I delete the agent schedule instances manually, it does not get recreated within ten minutes unless I restart my PRPC engine and all the nodes.

So not getting here who is The Agent Manager in PRPC system? Is it OOTB agent rule or some other process?

***Edited by Moderator Marissa to update platform capability tags****