How can to make required the fields keywords and description of the metatags module? I have a content type and I am interested in make required the field keyword and field description of the metatags module?  anyone knows how can I do it?

The field title is not required.
The field keywords is required
The field metatags is required.

I am working on drupal 7.  

Thanks a lot!!

I was trying this code:

function mymodule_form_alter(&amp;$form, &amp;$form_state) {
    if ($form['#form_id'] = 'article_node_form') {
        $form['#validate'][] = 'mymodule_form_validate_fields_metatags';
    }
}

function mymodule_validate_fields_metatags ($form, &amp;$form_state) {
     if (($form['#metatags']['metatags']['description']['value']) == '') {
        form_set_error('Description', t('The field Description is required'));
      } 
      if (($form['#metatags']['metatags']['keywords']['value']) == '') {
        form_set_error('', t('The field Keywords is required'));        
      }  

 }


this code generate an error : NOtice: undefined index. 

I have tried this code and not print dsm:

mymodule_form_alter(&amp;$form, &amp;$form_state) {
    if ($form['#form_id'] = 'article_node_form') {
        $form['#validate'][] = 'mymodule_form_validate_fields_metatags';
    }
}

function mymodule_form_validate_fields_metatags ($form, &amp;$form_state) {
dsm("hello");  

 }


if no print hello how can test the form_state?  I don't understand what is my error.  Thanks for your help in advance.
You can use code similar to the following in a custom module/theme:

function MYMODULE_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  if (isset($form['metatags'])) {
    if (isset($form['metatags']['description']['value'])) {
      $form['metatags']['description']['value']['#required'] = TRUE;
    }
    if (isset($form['metatags']['keywords']['value'])) {
      $form['metatags']['keywords']['value']['#required'] = TRUE;
    }
  }
}