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Prompting vs RAG vs Tool Use: A Decision Framework for Operators

Use a practical framework to choose between better prompts, retrieval systems, and tool integrations based on reliability and cost.

6 min readCebuano

A practical decision framework

Start with better prompting if knowledge is already in model context and reliability needs are moderate. Add RAG when accuracy depends on current internal knowledge. Add tool use when the agent must execute actions in external systems.

Use prompting when

Tasks are mostly reasoning and drafting, with low consequence if a human reviews output. Prompting is the fastest way to ship and validate value.

Use RAG or tools when

Use RAG for knowledge-grounded answers. Use tools for writes, updates, and external actions. Many strong systems combine both: RAG for context and tools for execution, with explicit approval gates.