First, I'd like to point out that, in the API page, Tags section, List subsection, it's missing the parameter "type".

Requested feature overview description.
An option to reverse the order of lists received via the API, and possibly the search engines, e.g. tag search.

Why would it be useful?
I reckon it's not needed, it would just make API-wrangling a bit easier.

What part(s) of the site page(s) are affected?
The API and the search engines.