diff --git a/specification/resources/resource-manager/Microsoft.Resources/stable/2018-05-01/resources.json b/specification/resources/resource-manager/Microsoft.Resources/stable/2018-05-01/resources.json
index 59f7d6482884..aeffab711b42 100644
--- a/specification/resources/resource-manager/Microsoft.Resources/stable/2018-05-01/resources.json
+++ b/specification/resources/resource-manager/Microsoft.Resources/stable/2018-05-01/resources.json
@@ -1022,7 +1022,7 @@
             "in": "path",
             "required": true,
             "type": "string",
-            "description": "The name of the resource group to create or update.",
+            "description": "The name of the resource group to create or update. Can include alphanumeric, underscore, parentheses, hyphen, period (except at end), and Unicode characters that match the allowed characters.",
             "pattern": "^[-\\w\\._\\(\\)]+$",
             "minLength": 1,
             "maxLength": 90