How to Begin Using LangSmith for Tracing - Part 1 of 6

Other Questions langsmith
1

I’m trying to learn LangSmith and want to start with the tracing functionality. This is the first part of what I hope will be a 6-part learning journey. I’ve heard that tracing is one of the core features of LangSmith but I’m not sure where to begin.

Can someone explain the basics of how tracing works in LangSmith? What are the key concepts I need to understand first? I’m looking for practical advice on setting up my first trace and understanding what information it captures.

Any beginner-friendly examples or step-by-step guidance would be really helpful. I want to make sure I build a solid foundation before moving on to more advanced topics.

2

hey owen! tracer logs everyithing ur LLM app does. just set LANGCHAIN_TRACING_V2=true and put ur API key. every chain/agent run gets traced auto - inputs, outputs, timings, all that. helps so much with debugging when things crash!

3

Think of tracing like a flight recorder for your LLM apps. I’ve used it for two years and it’s saved me countless times.

LangSmith creates a trace tree showing every step your app takes. Each node shows a component (chain, tool, retriever, etc) with inputs, outputs, and metadata.

What I tell new team members:

  1. Export these environment variables:
export LANGCHAIN_TRACING_V2=true
export LANGCHAIN_ENDPOINT=https://api.smith.langchain.com
export LANGCHAIN_API_KEY=your_key_here
  1. Run any LangChain code and check the Projects tab in your dashboard.

This shines when things break. Last month my RAG pipeline was slow as hell. The trace showed one retrieval step taking 8 seconds because of a bad vector store query. Fixed it in 10 minutes.

Start with something basic - a simple chain or agent. Skip custom runs for now and just get familiar with reading traces. The parent-child relationships click once you see a few examples.

What LLM app are you planning to trace first?

4

LangSmith tracing logs everything your language model app does. First, create a LangSmith account and grab your API credentials. Install the langsmith package, set your environment variables, and you’re done - tracing starts automatically without touching your code. You’ll get a hierarchical view showing how components connect, making it easy to spot bottlenecks and bugs. The web interface shows timing data and token usage to help optimize performance.