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### Answer Hello! It sounds like you're encountering inconsistencies with how parameter names are being handled in function calling. In Vapi, the parameter names should ideally remain consistent as defined. If there's a change in the case format or the formatting of these names, it might be due to how the parameters are parsed or serialized during the API's process. We have documented issues related to parameter names changing unexpectedly in environments like server message POST requests, as noted in a similar discussion where developers found variable name changes from snake_case to camelCase [(1)]() . While this appears in a non-official source and may not directly reflect your exact issue, it suggests there may be systemic reasons for these transformations, possibly related to internal handling or bugs. For a more controlled approach, ensure that your function definitions and calls in Vapi are strictly following the guidelines provided for function naming and parameter passing to prevent any unintended transformations. If this issue persists, it might be worth bringing up directly with the Vapi support or development team for a deeper investigation into how the system handles parameter serialization. Thank you for bringing this to attention, and please keep monitoring how these names are handled in your calls. If you have any more detailed logs or examples, these could be crucial for diagnosing the issue further.