title: Twitter card validation: Error with description tag
body: <p>I have each of the twitter meta tags as required by the <a href="https://dev.twitter.com/cards/types/summary" rel="nofollow">summary type</a> of twitter cards for an example page on my site (Drupal-based, as configured from the Global page settings in the Metatags module):</p>
  
  <pre><code>&lt;meta name="twitter:card" content="summary" /&gt;
  &lt;meta name="twitter:site" content="@detaildata" /&gt;
  &lt;meta name="twitter:url" content="http://data.nicva.org/article/access-research-knowledge-northern-irelands-social-issues" /&gt;
  &lt;meta name="twitter:title" content="Access Research Knowledge on Northern Ireland&amp;#039;s social issues" /&gt;
  &lt;meta name="twitter:description" content="The Detail Data Portal is a publicly-accessible data catalogue for open data from all sectors in Northern Ireland" /&gt;
  </code></pre>
  
  <p>However, the card <a href="https://cards-dev.twitter.com/validator" rel="nofollow">validator</a> returns the error message wrt the description field:</p>
  
  <pre><code>ERROR: Invalid value (message: Field description failed to validate because: text expects tag property, but not found in Map().)
  </code></pre>
  
  <p>I don't understand what "text expects tag property, but not found in Map()" refers to. Can anyone shed any light on what that is and why the card is not validating for any of my pages?</p>