ESPHome and services UI

For my Sonoff RF Bridge with ESPHome I defined some services to send/receive/activate.
I have no idea if it’s possible to give hints to HA from ESPHome about which variables to expect for a service. In the new UI for services I now select a service provided by ESPHome and that’s it, no visual clues that I might need to input something and if I then go into “YAML mode” things don’t get any clearer.
I would suggest at least some information in the new UI about how things work visually, but also a little hint that in “YAML mode”, you actually have to define “data” with variable names underneath that…
Maybe it’s ESPHome, maybe it’s HA, but right now the services UI for the combination is not intuitive…