Como listar as teclas de um aplicativo de função azul usando a função ARM listKeys?

Meu modelo:

 {
    "$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {},
    "resources": [],
    "outputs": {
        "referenceOutput": {
            "type": "object",
            "value": "[listkeys(resourceId('Microsoft.Web/sites/functions', 'my-function-app','my-function'),'2016-08-01').key]"
        }
    }

E então execute com:

az group deployment create -g my-rg --template-file ./arm.json --mode incremental

Erro:

No route registered for '/api/functions/my-function/listkeys?api-version=2016-08-01'