How are descriptions determined for non-post pages?

[naddeoa]

I've got a few non-post markdown pages on my site and it looks like the descriptions for those pages are determined to be more or less the entire content of the page, including script tags.

This is an example: https://naddeo.org/pokeboard/?mode=TypeFilterSearch&primary=ground&secondary=

It doesn't look like there are any metatags that can be used in non-post pages to explicitly set the description and I'm using the default template with

<meta name="description" content="@|description|">

Could you point me in the right direction to the code that determines what the description template variable should be? I'd like to explicitly set it in my non-post page or create some other way of overriding it.