What is my DSCResource does not require any input parameters?

Might be a stupid question but DSCResource schema requires me to have input parameter. But what is it’s not required for my resource? Example is I want to make sure that there are no empty application pools on machine? Resource checks if any application pools do not have associated applications with it and then deletes them.
Do I still need to have input parameter specified?

So far, I’ve mainly seen people add a “dummy” property to fill the requirement.

You at least need a key property in your resource in a way that multiple instances of your resource is not allowed. This Bloghas more details on how to write a resource with single instance.