Creating a low toner alert and testing alerts, how to?

I have encountered multiple people online creating toner alerts for their printers using the alerts menu, it seems the syntax changed from “toner.etcetc” to “printer.etcetc” a while back.

What I’d like to do, is configure an alert for devices with less than say, 10% toner across the fleet. Specifically only the ‘normal’ print consumables, the 3 colours and black and white, no waste bins or fusers etc.

My current rule is
“printer_supplies.supply_current”
less or equal
5

That’s it, just 5.
How do I define 5% for example?
Is there a way I can isolate it to just certain toners?

Am I doing it correctly? I’m attempting to identify the correct syntax.
Is there a simple guide on how to do this properly?

I’d also like to fake test the alert, is that possible somehow, just to see which devices would be audited by my alert / filter?