The API works the best with article and content website URLs (full URL). You should avoid sending IP-addresses, technical URLs (e.g. like dynamic AdServer URLs, CDN and storage URLs (like cdn3.xyzdomain.com) or any other URL which is not related to some content.
No content – no contextual analysis. It is simple like that.
You should filter up front which URLs you want to be analyzed by our API. This might help you to save costs too.