How to verify that SEO is working?

I’m using the manuelschoebel:ms-seo package, and I’d like to verify that it’s working. How do I do this?

I tried this tool:

It says there’s no meta description for the site I’m working on, though I’m using the package’s SeoCollection collection properly and there’s data in there for the appropriate routes.

The spiderable package is installed too. I’m using mup to deploy.

I tried feeding the URL into the above tool and added ?_escaped_fragment_= to the end of the URL. It did fetch more information (such as alt tags), but still not the meta information.