So I found this list of webservice api calls: https://docs.moodle.org/dev/Web_service_API_functions
Unfortunately I cannot use most of it's functions because many of them require additional arguments, Without them I always get an invalidparameter error response. But I can't find any documentation on which parameters are required. So If you know a link to a detailed documentation of every function please tell me. Especially core_calendar_get_calendar_monthly_view and core_calendar_get_calendar_events are important for me but a list of everything would be even better.