Can you clarify what you’re trying to do? The SharpTools Rule Engine should expose whatever commands the device exposes.
(I don’t have a Honeywell Evohome, so this is just an example screenshot)
If the DTH has been updated recently and new commands or parameters were added, you may want to reauthorize the device starting from your SharpTools.io User Page to make sure the new details get synced over.
I would also add that there may be use-cases with custom device handlers where you may want to customize what parameters are sent with a command and you can do that with the Advanced toggle.
To @Andremain’s point, SmartThings will be deprecating Groovy SmartApp integrations at some point in favor of their new REST API. (And at some point will be deprecating Groovy DTH’s too). The new REST APIs require that a device either strictly follows the official capabilities or that it defines a Custom Capability. I only mention this because at some point the device will either have to be updated with a Custom Capability or use standard capability definitions or any custom commands will eventually become unusable.