Nosto supports tagging the rating and review metadata. The rating value and review count metadata can be used for creating advanced recommendation rules to promote products that are well reviewed.
The rating values can also be used to show star-ratings in your recommendation and email templates.
The ratings and reviews metadata collection are disabled by default. You can toggle the ratings and reviews metadata collection by navigating to the configuration page and toggling Ratings source to Magento's native product reviews under the Ratings & Reviews section.
Once you've enabled the rating and reviews metadata, you should be able to see the new product metadata collected by Nosto.