Dougal Campbell

HeadMeta creates <code><meta></code> “description” or “keywords” tags for individual 
posts or pages. It can also create arbitrary <code><meta></code> or <code><link></code> tags. 
These are easily set on a per-post (or page) basis by simply adding Custom 
Fields.
See the Installation section for more detailed examples.

HeadMeta

Automatically add <link>, <meta> description and <meta> keywords to your HTML on a per-post (or page) basis.

jim912

Outputs meta description and meta keywords in the element head. 
Notice! Current version japanese only, yet.
<h3>Links</h3>
“<a href="https://wordpress.org/extend/plugins/ps-auto-sitemap/" title="WordPress sitemap plugin">PS Auto Sitemap</a>” is a plugin automatically generates a site map page from your WordPress site. 
It is easy to install for beginners and easy to customize for experts. 
It can change the settings of the display of the lists from administration page, several neat CSS skins for the site map tree are prepared.
“<a href="https://wordpress.org/extend/plugins/ps-disable-auto-formatting/" title="WordPress formatting plugin">PS Disable Auto Formatting</a>” 
Stops the automatic forming and the HTML tag removal in the html mode of WordPress, and generates a natural paragraph and changing line.
“<a href="http://www.web-strategy.jp/" title="CMS service with WordPress" rel="nofollow ugc">CMS service with WordPress</a>” provides you service that uses WordPress as a CMS.

Meta Manager

Outputs meta description and meta keywords in the element head.

HeadMeta vs Meta Manager