diff --git a/readme.md b/readme.md
index 5430755..f807eb6 100644
--- a/readme.md
+++ b/readme.md
@@ -18,6 +18,8 @@ brew install skipctl
 The various `test` commands will execute against an API server. Run `skipctl test ping --api-server=something` to get a list of supported API server names.
 An API server represents a location that can run tests from their perspective. All communication with API servers is encrypted over TLS.
 
+> :exclamation: Before issuing any commands, be sure to be authenticated first (`gcloud auth application-default login`). 
+
 ### Ping
 
 ```shell