Prompt Patterns for RAG
Retrieval-Augmented Generation (RAG) combines a retrieval step with an LLM to ground outputs in external documents. Good prompt patterns make RAG systems more reliable and easier to evaluate.
Core patterns
- Context + Instruction: Include the retrieved passages first, then a clear instruction: “Given the context below, answer concisely and cite the source IDs used.”
- Concise Fusion: When many passages are returned, ask the model to synthesize only the most relevant 2–3 points.
- Fallback Behavior: Explicitly instruct what to do when the context doesn’t contain an answer: return “No answer in provided context.”.
Formatting and citation
- Request inline citations like
(doc-123)and a short sources list at the end. - Limit token use by asking for summaries rather than verbatim repeats of context.
Evaluation tips
- Test with out-of-context questions to confirm the model refuses to hallucinate.
- Measure faithfulness by comparing generated citations to the actual retrieved passages.
Practical adoption of these patterns reduces hallucinations and improves traceability for RAG applications.