Extend header

I am trying to extend the header with an excerpt to be put in meta description tag. Title and tags are not an issue to manipulate, but description is bugging me.

Whatever I try, it does not display. It works for users, just echo $user->description but for objects like blogs it does not seem to work.

This is the simple code snippet :

$article = $vars['entity'];

$description = elgg_get_excerpt($article->description, 170);

      ?>

<meta name="description" content="<?php echo $description;?>" />

Dynamic descriptions are valueable to search engines. Most of the time they take over what you provide here so it is important that the text is what the users wants to communicate. This normally is what they provide as excerpt.

 

Ps: var_dump $description says string(0) bool(false)