This native Joomla 1.5 plugin automatically generates keywords and description by pulling text from the title and the content to help with SEO. It also gives you the ability to set different title configurations.
The description isn't saved in the article but the search engine can get it from the source text.
The keywords are normaly not saved but you can save, delete or change the keywords for all articles by changing the options "Regenerate All Keywords and save it" and "Minimum Word Length" or the "Keywords-Blacklist".
Joomla SEO metadata by SEO-Generator plugin