digrart

This plugin allows you to add a meta description to each post, page, or custom post type as well as archives and taxonomies directly from the WordPress editor. Simplify SEO for your WordPress site without any extra fluff.

dig Description

Just the Meta Description. / 投稿ページやアーカイブページに、ただディスクリプションを設定できるだけのプラグインです。

Epigrade

Add page title, meta description, keywords and robots to all post types and taxonomies. 
Plugin will automatically change page titles for posts, pages, custom posts, categories, tags and custom taxonomies to 
whatever you have entered. Also will inject meta fields in template head section. If however you leave fields empty 
default WordPress or theme behaviour will occur. 
This plugin also removes taxonomy description column from listing table.
You can use it in your theme or other plugin. It creates the following taxonomy and post meta fields: 
 _page_title, <code>_meta_description</code>, <code>_meta_keywords</code>, <code>_meta_robots</code>.
Example usage:
<pre><code>// Get page title value for taxonomy with ID $term_id:
$taxonomy_title = get_term_meta( $term_id, '_page_title', true );

// Get page title value for post with ID $post->ID:
$post_title = get_post_meta( $post->ID, '_page_title', true );
</code></pre>

WP Simple SEO Meta

Add page title, meta description, keywords and robots to all post types and taxonomies.

dig Description vs WP Simple SEO Meta