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>
    <pageswithprop>
      <page pageid="1704" ns="0" title="Тайник/ru" value="Тайник" />
      <page pageid="1707" ns="0" title="Тайник/en" value="Cache" />
      <page pageid="1710" ns="0" title="Бонусы ландшафта/en" value="Landscape Bonuses" />
      <page pageid="1713" ns="0" title="Кладовая/en" value="Strongbox" />
      <page pageid="1740" ns="0" title="Кладовая/ru" value="Кладовая" />
      <page pageid="1742" ns="0" title="Бонусы ландшафта/ru" value="Бонусы ландшафта" />
    </pageswithprop>
  </query>
</api>