RAG systems live or die on metadata. Without it, retrieval becomes noisy, permissions are fragile, and relevance is inconsistent. With strong metadata, you can enforce access control, improve ranking, and explain results.
Start with a clear taxonomy
Define the minimum metadata fields that matter:
- Source system. Where the content came from and its owner.
- Content type. Policy, FAQ, runbook, contract, ticket.
- Domain tags. Product line, region, business unit.
- Freshness markers. Updated date, effective date, expiry date.
Permissions must be metadata-first
Permissions should never be enforced in prompts. Use metadata fields for tenant and role access, then filter at retrieval time (see knowledge base governance and multi-tenancy).
Metadata improves ranking
Metadata enables better relevance:
- Boost content that matches the user region or product.
- Down-rank stale or superseded content.
- Use metadata filters in hybrid search and reranking (see ranking and relevance).
Operate metadata like a product
Metadata quality degrades over time if it is not maintained. Make it part of ingestion pipelines and quality checks (see ingestion pipelines). Track missing or inconsistent fields and fix them before they damage retrieval quality.
A strong metadata strategy is the quiet foundation of reliable RAG systems.