Paste the following code into your functions.php file:
function create_meta_desc() { global $post; if (!is_single()) { return; } $meta = strip_tags($post->post_content); $meta = strip_shortcodes($post->post_content); $meta = str_replace(array("\n", "\r", "\t"), ' ', $meta); $meta = substr($meta, 0, 125); echo "<meta name='description' content='$meta' />"; } add_action('wp_head', 'create_meta_desc');
Thanks to Paul for this handy snippet!