How to list the @Cities entity values my Bot works with in Watson Conversation Service

I have an Entity @City = Austin, Providence, London and Boston I simply want to answer the question what cities does this bot work with?

And then respond with:

Here are the cities this works with $Locations ,  Which city do you want?

In the dialog, you have access to all the entities that were detected (recognized) in the user input. However, you do not have access to all the defined entities and their possible values.

What you could do is to define a context variable with the allowed values. That variable could even be dynamically populated (see this tutorial for database access from within Watson Assistant). Another option is to hardcode the response. But this only works well with few values and infrequent changes.