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-continue>
    <alltransclusions gatcontinue="Category_to_Skill|2616" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1603" ns="14" title="Category:Long blades" />
      <page pageid="1795" ns="14" title="Category:Theory of electrical engineering" />
      <page pageid="1957" ns="14" title="Category:Enhance criticals" />
      <page pageid="2044" ns="14" title="Category:Martial arts" />
      <page pageid="2064" ns="14" title="Category:Fishing" />
      <page pageid="2181" ns="14" title="Category:Mana control" />
      <page pageid="2340" ns="14" title="Category:Repair armour" />
      <page pageid="2344" ns="14" title="Category:Attack" />
      <page pageid="2365" ns="14" title="Category:Theory of pyromania" />
      <page pageid="2370" ns="14" title="Category:Mastery of shielding" />
    </pages>
  </query>
</api>