Check if WordPress site description is default, show notice to update

wp-update_tagline.php

<?php
/**
 * Checks to see if your tagline is set to the default and shows an admin notice to update it
 * Throw this in function.php for your theme
 */
if (get_option('blogdescription') == 'Just another WordPress site') { add_action('admin_notices', create_function( '', "echo '<div class=\"error\"><p>".sprintf(__('Please update your <a href="%s">tagline</a>', 'bb'), admin_url('options-general.php'))."</p></div>';" ) ); };

// Different approach

/**
 * Don't return the default description in the RSS feed if it hasn't been changed
 */
function roots_remove_default_description($bloginfo) {
  $default_tagline = 'Just another WordPress site';

  return ($bloginfo === $default_tagline) ? '' : $bloginfo;
}

add_filter('get_bloginfo_rss', 'roots_remove_default_description');

?>