When I am testing my Google Action bot in Google Action Developer Tool the Simulator does not work.
For testing your Google Actions in the Google Actions Simulator, you need some special permissions on your Google account enabled for the Simulator to work.
Make sure your Web App permissions are enabled for your Google Account.
To grant other needed permissions, try invoking your Google App from the Google Assistant on your Physical Device (e.g. Phone or Google Home).
Make sure that in the test Simulator settings "On device testing" is enabled.
Type or say the invocation phrase on any Assistant enabled device you're logged into, with the Google account you are developing your action in. It should invoke the test version of your action.