LangSmith Tracing & Testing
Trace, test, and evaluate LLM and RAG apps with LangSmith. Validate that every query is traced, build evaluation datasets, catch regressions, and turn production traces into repeatable tests.
This skill adds LangSmith observability and testing to LLM applications. It instruments chains and agents so every query produces a trace, verifies retrieval steps are captured for RAG, builds datasets and evaluators to score outputs, compares versions to catch regressions, and promotes interesting production traces into a regression test suite.
langsmith llm-eval tracing testing rag
When to use
Use when you need tracing, evaluation datasets, or regression testing for an LLM, RAG, or agent app, especially in the LangChain ecosystem.
Examples
Trace every query
Instrument a RAG chain
Add LangSmith tracing to my RAG chain and assert that retrieval and generation are captured for each query
Build an eval dataset
Score outputs and catch regressions
Create a LangSmith evaluation dataset from production traces and run an evaluator that flags answers that got worse after my prompt change