Some search engines use HTML "meta" tags to assist in classifying sites they index. While there is no dedicated tool in the Geodesic Admin to manage meta tags, it is easy to specify them on a site wide basis within the default design. The default head.tpl file included with the software already has an example you can follow. Look for the following HTML in that file:

<meta name="Keywords" content="KEYWORDS GO HERE" />
<meta name="Description" content="DESCRIPTION GOES HERE" />

and replace "KEYWORDS GO HERE" and "DESCRIPTION GOES HERE" with your keywords and description, respectively.