My Moodle installation on "Site administration - Plugins - Web services - External services - Functions" lists all the function available for external API - to be exact, to the service "Moodle mobile web service".
The list has only 20% from all the functions described in API documentation. For example, it has moodle_user_get_users_by_id function which returns a correct result when called from API. But when I try to call the function I need - core_user_get_users - which is not listed on that page, I get webservice_access_exception as result.
There are on buttons or links which could add API access rights to the required functions.
I don't say the API rights system is overcomplicated (while it is) - please anyone tell me how to make API calls for core_user_get_users done right?