what would be the best way to take a list of busy times, such as from gcal, and converting it to a string of available times for the vapi agent to easily understand without needing to use an llm to process the busy times. I've noticed feeding busy times into vapi and trying to get it to pull available times by determining the times without events is very unpredictable. The most consistent method ive been using is using a chatgpt module in Make but that ends up adding about 10-15 seconds of latency when calling my checkAvailability tool.