Steve

This plugin uses custom fields to allow the page title tag to be customised and differ from the actual page title.
Both meta descriptions and keywords can also be added if required.
Page meta details can be modified on any publicly accessible post type, such as posts and pages, as well as custom post types.
Theme and plugin developers should note that it is possible override the page title within your templates by setting <code>$wppm_title = 'Newly defined title';</code> before the call to <code>get_header();</code>.

Page Meta

Adds the ability to override the page meta title and add in meta descriptions and keywords for pages.

thomascharbit

Add a description to all WooCommerce shipping methods on cart and checkout pages. 
Compatible with WPML and Polylang for translations.

Shipping Method Description for WooCommerce

Add a description to all WooCommerce shipping methods on cart and checkout pages.

Page Meta vs Shipping Method Description for WooCommerce