filtered_html in theme-settings.php
Try this:

$form['options']['description'] = array(
'#type'          =&gt; 'text_format',
'#title'         =&gt; t('Description'),
'#default_value' =&gt; theme_get_setting('description'),
'#format'        =&gt; 'filtered_html',
);


https://api.drupal.org/api/drupal/developer!topics!forms_api_reference.html/7.x/#text_format