Thanks to @Mark_Johnson to pointed me to this:
Log in to your site as an administrator, and go to Site Administration > Server > Web Services > API Documentation
This will list all the web service functions currently available on your site, which you can expand to show details of the parameters.
The direct link is something like this:
https://mydomain.com/moodle/admin/webservice/documentation.php
This will list all the web service functions currently available on your site, which you can expand to show details of the parameters.
The direct link is something like this:
https://mydomain.com/moodle/admin/webservice/documentation.php