You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query>
    <pages>
      <page pageid="1312" ns="0" title="Sybase installation" />
      <page pageid="1337" ns="0" title="Sybase and Xen" />
      <page pageid="1357" ns="0" title="WebServices" />
      <page pageid="1367" ns="0" title="Fixing system tables in the master database after a change of Characterset/SortOrder" />
      <page pageid="1407" ns="0" title="Corruption of syslogs" />
      <page pageid="1409" ns="0" title="Installation guidelines IQ" />
      <page pageid="1415" ns="0" title="Installation guidelines ASE" />
    </pages>
  </query>
</api>