----------------------------- **While I generate an answer, here are some sources that might be helpful**: * [Server URLs]() * [Outbound Sales Example]() * [Glossary]() * [Function Calling]() -----------------------------

### Answer It seems like the behavior you're experiencing with the "book appointment" function might be related to how the function is configured within your Vapi assistant. If the function continues to trigger the webhook even when the time is not available, there might be a loop or a recurrent trigger mechanism set up unintentionally. You can control how and when functions are triggered by setting conditions within the assistant's configuration. Ensure that the function calling mechanism is configured to handle failure responses appropriately and doesn’t re-trigger under the same conditions unless specified. Here's a general approach to modify the function calling condition: 1. Check the function's trigger conditions within your assistant's configuration. Make sure it is set to trigger only when the specific conditions are met. 2. Implement logic on your server endpoint to handle different responses. For instance, modify the response handling logic so that it does not re-trigger the function unnecessarily when the "time not available" message is received. 3. Utilize the

result

property to communicate the outcome back to the assistant, allowing it to handle the flow correctly based on the response [(1)]() . Here is an example of how you might configure the server response to handle failure:

json
{
  "result": "The appointment time is unavailable, please try another time."
}

This example ensures that the function calling mechanism in Vapi gets a clear response indicating that the time slot isn't available, which should prevent it from triggering the webhook again under the same circumstances. For more detailed guidance on handling function calls and designing robust error handling within your Vapi assistant, you can refer to the function calling documentation.

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check this docs