When your LangGraph agent runs, a lot happens under the hood. If it gives a wrong answer, you need to know: Was it a bad retrieval? Did the tool fail? Or did the LLM just misinterpret the data? LangSmith allows you to trace every single step. Tracing: See the exact prompt sent and the raw JSON returned. Latency: Find out which node is slowing down your app. Cost: Track exactly how many tokens that "loop" consumed. Pro Tip: Simply setting two environment variables in your .env file enables t...