If you are talking about product description then unique content can give positive SEO benefits rather than 100 products with the same description which will be viewed as duplicate content.
If you are talking about meta descriptions... (from this post)
Not a Google Ranking Factor
Google announced in September of 2009 that neither meta descriptions
nor meta keywords factor into Google's ranking algorithms for web
search. Google uses meta descriptions to return results when searchers
use advanced search operators to match meta tag content, as well as to
pull preview snippets on search result pages, but it's important to
note that meta descriptions do not to influence Google's ranking
algorithms for normal web search.