On both desktop and mobile TOC should be equipped with:
TOC will be brought to immediate attention of blind users. Screenreaders are supposed to offer in first place, after alerts, the navigation elements pointing to related other pages and the major navigation within the page.
A similar concept is <nav> in Grouping content@HTML. The role="navigation" attribute is telling the screenreader that this <div> element is playing the same role.
<div id="toc" class="toc" role="navigation">
This is a follow-up of T26659 from 2010/2016.