when do you start thinking about distributed tracing

hey everyone, ive been working with a few microservices lately and the interactions between them are starting to get tricky to debug. Tracing requests across service boundaries feels like it's becoming a real pain. I've read about tools like Jaeger and Zipkin, but I'm wondering at what point the complexity of setting them up is justified. When did you first decide you needed distributed tracing in your system? What were the warning signs?