Hey!! New Vapi user here trying to figure out how to get my voice agent to query my web server and access relevant data before responding. I've built my web server to give responses to when a tool is called with the appropriate JSON format configured as given in here: https://docs.vapi.ai/tools/custom-tools#adding-more-tools. Trying to make the tool query my server, but it's not quite working (when I go to "Test Tool" in the Vapi dashboard, the error is "Load Failed". Please advise?