Using schema.org semantics to describe content allows search engines (Google, Bing, Yahoo, Yandex) to comprehend the content of web pages. Google, for example, can use these semantics to present search results with rich snippets (contextually better layouts).
If you’ve ever tried working with schema.org markup, you might find it can be a little complicated. Hopefully this tool will help. The user interface isn’t fabulous, but the tool itself seems to work.
It looks like you can use this link to build your own schema: http://polak.es/en/ontology.html
And you can use this to generate descriptions using existing schema.org schema: https://schema.pythonanywhere.com/