Choose "Google Assistant" as the Service
Choose "Say a phrase with a text ingredient"
Enter some phrases with a $ placeholders like: "Turn the light $" (figure 1) and choose your language.
Click "Create Trigger"
Choose "Webhooks" (figure 2) as your action service.
Fill in the webhook form
Open the Web-App, go to settings and create your personal access token. (figure 3)
"userid": "YOUR USERID",
"token": "YOUR ACCESS TOKEN",
Click "Create Action"
That's it. Now enjoy using your voice to control your home. The API understands a lot of colors and all the named gradients you have saved. If you discover that the Assistant doesn't understand some words correctly, you can give your lamps and groups "tags" which will be handled like aliases.