How to Debug a RAG System: A Six-Step Framework from Retrieval to Guardrails

ashishllm · x · 2026-09-16

A systematic answer to the interview question "how do you debug a RAG system that feeds users wrong information," laid out in six steps:

Test retrieval first: measure precision, recall, MRR and hit rate on an eval set; if below thresholds, switch from pure semantic search to hybrid search.
Confidence thresholding: add a Reranker after retrieval and return "No Context Found" when confidence is too low instead of serving irrelevant answers.
Query expansion: expand and correct user queries per domain to improve the keyword side of hybrid retrieval.
Prompt tuning and guardrails: only generate when the Reranker passes confidence checks; add few-shot examples.
Chunking strategy: check overlap settings, layout-aware or paragraph-level chunking.
Higher embedding dimensions: better retrieval quality at the cost of latency and cost.

The author promotes paid 1:1 career consultations at the end, but the debugging framework itself is practically useful.

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