General developer forum

You should be able to declare any capabilities you wish to use in the yourpluginname/db/access.php file, and then you would be responsible for checking that the user has that capability in that context when you are writing your customised code.

For example, say you have defined a capability called mod/yourpluginname:tagerrors in your db/access.php.

You would then need to check whether the user has this capability, when you are providing the means for them to tag errors.

e.g. something like this (obviously I've not fully implemented this so I can't guarantee this is 100% right)

// Get the context first
$context = context_course::instance($courseid); // Assuming this is a feedback activity viewed from within a course page

// Does the user have this capability in this context?
if(has_capability('mod/yourpluginname:tagerrors', $context)) {
    // Code to display the button to tag errors goes here
    // ....
} else {
    // Code to do something else goes here - you might just not show anything
    // ....
}