This article has these four metadata tags:
Title: Minimal metadata
Slug: minimal-metadata
Tags: pelican, publishing
Summary: How little metadata can an article get away with?
The filepath used is /posts/2014/12/07_minimal-metadata.md
How does Pelican know what to do with it?
Easy: the date is given as part of the filename. The slug and title are taken from the article.
To go really lightweight, remove tags and summary.