[SOLVED]How do I set a tooltip description for a pie submenu (not the operator)?

I’m currently writing a python add-on.
All is fine with setting the tooltip on an operator pie “leaf” by setting bl_description=“whatever”.
But I cannot find any documentation on how to set the tooltip description for a pie submenu.
All I get in the tooltip is: "Call (draw) a pre-defined pie menu."
Can it be done?

Never mind.

Seems like I followed a bad code example, adding a sub-menu by doing:

pie.operator("wm.call_menu_pie", text="Some Title").name="Menu class name"

The proper way of doing it, with pie.menu(…) does NOT produce a tooltip
that looks like a bad default placeholder.