Prerequisites: You have successfully deployed the weatherWebhook cloud function from your command line and also made a note of the httpsTrigger URL
Back inside your API.AI agent, first copy/paste your new httpsTrigger URL into the Fulfillment section.
In the AskForWeather intent, add a required parameter of type @sys.geo-city and call it “geo-city”. Note: you must use this exact name and system entity type. Don’t use your own variable name, at least not at this point.
Under prompts, you can have something like “Which city?”
Remember to Save the intent.