how are people actually debugging bad outputs in agent / RAG pipelines?

Reddit r/LocalLLaMA / 4/10/2026

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Key Points

  • The post focuses on real-world debugging of agent/RAG systems where everything “works” (tool calls succeed and parsing passes) but the final answer is still incorrect or slightly off.
  • It asks the community how they diagnose these silent failure modes in practice, especially when there are no crashes or hard errors.
  • The author highlights common approaches people might use, including evals, tracing/debugging tools like LangSmith, manual log inspection, or simply tolerating a percentage of bad outputs.
  • The underlying problem is that model quality and retrieval/planning dynamics can fail even when pipeline execution appears healthy, making debugging more about assessing behavior than catching exceptions.

been messing around with some agent / RAG pipelines

running into cases where everything executes fine (tool calls return expected outputs, parsing works etc.) but final answer is still wrong / slightly off

nothing crashes, just bad outputs

curious how people are actually debugging this in practice

are you:

  • using evals?
  • tracing tools (langsmith etc)?
  • stepping through logs manually?
  • or just accepting some % of bad outputs

feels like a lot of cases where nothing technically fails but output is still wrong

submitted by /u/YouSlow6554
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