Corrective RAG (CRAG): Self-Evaluating Retrieval

~12 min read

Corrective RAG adds a validation step after retrieval: check retrieved results against trusted sources before trusting them, and fall back to a web search when the vector store's results aren't good enough.

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Key points

  • CRAG adds a relevance-evaluation step between retrieval and generation — retrieved content isn't automatically trusted
  • The evaluator scores retrieved chunks for genuine relevance/trustworthiness, not just cosine similarity
  • Sufficiently relevant content proceeds like naive RAG; insufficient content triggers a fallback to an external source like web search
  • Especially valuable for fast-changing information, where a vector store's static content can be stale even when it's the closest semantic match
  • Trade-off: more robust retrieval at the cost of an extra evaluation step (and possibly a web search call) in the pipeline