"As a Reader, I want to read the most appropriate article short description in the search results for the REST API search endpoints, so that I can make an informed decision about the results."
The endpoints for the full-text (/search/page) and title search (/search/title) for the MediaWiki REST API return the description for articles in the output.
On English Wikipedia, these should return the local description page property. For other wikis, it should return the Wikidata description.