This feature was not implemented by the Wikidata / WIkibase team and is not maintained by the team either.
It was introduced in {T184000} and even then it probably should not have been added to Wikibase.git
Right now I would propose that this be moved to some extension controlled and owned by whichever WMF team owns this feature, OR to a package within Wikibase.git that has clearly defined owners.
Quickly looking through the code it would appear that this would be:
- definition of 2 magic words
- 2 config settings
- localization messages
- The API implementation `Wikibase\Client\Api\Description`
- A hook handler `Wikibase\Client\Hooks\DescriptionProviderHookHandler`
- The parser function handler `Wikibase\Client\Hooks\ShortDescHandler`
- UsageLookup for the feature
And it may also require a new hook or extension mechanism for this usage related bit.