Hi @Aaron Manill thanks for the question,
There is no "hidden" cost for SignalR Live Trace Tool. But keep in mind that live traces are counted as outbound messages that will be charged. Please see this doc for more information:
https://learn.microsoft.com/en-us/azure/azure-signalr/signalr-howto-troubleshoot-live-trace
https://azure.microsoft.com/en-us/pricing/details/signalr-service/
hope that helps.
-Grace