It seems that the 'content' tag of the atom feed is meant to be filled out with
the build description (as indicated by atom.jelly from the source code):

<j:forEach var="e" items="${entries}" >
<entry>
<title>${h.xmlEscape(adapter.getEntryTitle(e))}</title>
<link rel="alternate" type="text/html"
href="${rootURL}${h.encode(adapter.getEntryUrl(e))}"/>
<id>${adapter.getEntryID(e)}</id>
<published>${h.xsDate(adapter.getEntryTimestamp(e))}</published>
<updated>${h.xsDate(adapter.getEntryTimestamp(e))}</updated>
<j:set var="desc" value="${adapter.getEntryDescription(e)}"/>
<j:if test="${desc!=null}">
<content>${h.xmlEscape(desc)}</content>
</j:if>
</entry>
</j:forEach>

However - it is always empty. We're on v1.304 - but I didn't see anything in
subsequent change logs that would indicate that this is a bug that has been fixed.

Thanks