Input field help message based on connection parameter for my Integromat app

I want to generate a help directive whose text depends on a connection parameter. Trying to use a curly bracket expression doesn't work.

{
  "type": "text",
  "label":"Relative URL",
  "name":"url",
  "help":"Enter a path relative to `{{connection.workspaceUrl}}`.",
}

How can this be done?

It is not possible to do it directly the way you've tried it but you can use RPC for that.

Steps how to use RPC:

• Set Mappable parameters of your module to:

"rpc://rpcGetInputParams"

• Create RPC with name rpcGetInputParams
• Set Communication of the RPC to:

{
    "response": {
        "output": [
            {
                "type": "text",
                "label":"Relative URL",
                "name":"URL",
                "help":"Enter a path relative to `{{connection.workspaceUrl}}`.",
            }
        ]
    }
}

(it is possible to call RPC without calling the 3rd party service. More info here.)