Struggling with implementing the AI through Vapi to book into google calendar, doesn't seem to be pulling through {{1.message.toolCalls[].function.arguments.BookingTime}}

Hi All, New here so not sure where to start for this information, however I have made AI automations previously with Vapi and have figured out through Brendans video on connecting VAPI to Make to call the client. How would you go about making the call personalised? I.e i specifically want the AI vapi agent to phone the client and say "Hi 'clientsname'" that we have taken from the form.