My arc_meta Textpattern plugin has been updated with new tags for meta robots and keywords.
<txp:arc_meta_robots /> will output a robots meta tag for instructing search engine crawlers how to index your site. You can set the specific instructions for each article, section and category. If you’re site’s production status is testing or debugging the tag will automatically output a
noindex, nofollow robot tag so that the page isn’t indexed.
<txp:arc_meta_keywords /> only works for articles and utilises Textpattern’s keywords field to output a keywords meta tag. I was originally hesitant about adding support for this as they’re generally of little use, but apparently are useful for some sites.
The next plan for the plugin is to provide a page for editing the meta data for sections under the ‘Content’ tab.