This property provides a "shortest possible" type of description, typically less than a short sentence, used for example to describe a piece of software, or a resource, or a method or anything else really.
It should be used as such:
<page name> is (a/an/the/...) [[description::as little text as possible]].
HMMER is a [[description::software package for working with profile hidden Markov models (HMM)]].
Note that neither "page title", nor "is a", nor the full stop character are part of the description, much like Debian package descriptions.
The intended benefit for using this property would be within dynamically generated tables, where it will typically appear as short "description" column.