diff --git a/docs/guide/devtools.md b/docs/guide/devtools.md
index 970b8f768..316471eba 100644
--- a/docs/guide/devtools.md
+++ b/docs/guide/devtools.md
@@ -23,7 +23,7 @@ You can run Textual apps with the `run` subcommand. If you supply a path to a Py
 textual run my_app.py
 ```
 
-The `run` sub-command assumes you have an `App` instance called `app` in the global scope of your Python file. If the application is called something different, you can specify it with a colon following the filename:
+The `run` sub-command will look to see if you have an `App` instance called `app` in the global scope of your Python file and will use that if it does. If not it will then look to see if there is a class that inherits from `App` and it will create and `run` an instance of that. Finally, you can specify the application instance to run with a colon following the filename:
 
 ```bash
 textual run my_app.py:alternative_app