Same topic, related formats. Practice these next.
RAG is a retrieval pattern that injects documents before generation; MCP is a connection protocol for tools and data. They are different layers, and MCP can expose RAG as one tool.
Picture a chef in a kitchen. RAG is like prepping ingredients before service: you gather the right items and lay them on the counter so the chef has them on hand while cooking. MCP is the standardized plumbing and power sockets in the kitchen: it lets the chef plug in any appliance, a blender, an oven, a scale, from any brand without rewiring. One is a way of getting facts ready before you start. The other is a wiring standard that lets the chef reach live tools and data while working. You can even build a 'fetch the right ingredients' appliance and plug it in through that standard plumbing. So they are not rivals; one can sit inside the other.
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example.
Everything important, quickly.
4 min: RAG as a retrieval pattern + MCP as a connection protocol + the containment relationship + when to pick each + how they compose in a real agent.
| Concern | RAG | MCP |
|---|---|---|
| What it is | Retrieval pattern | Connection protocol |
| When it runs | Once, before generation | At runtime, mid-conversation |
| Primary job | Ground the answer in a corpus | Wire the app to tools, data, prompts |
| Transport | None; just prompt assembly | JSON-RPC over stdio or streamable HTTP |
| Containment | Cannot wrap MCP | Can expose RAG as one tool |
Real products, models, and research that use this idea.
What an interviewer would ask next. Try answering before peeking at the approach.
Red flags and common mistakes that signal junior thinking. Click to expand.
Treating MCP as a newer replacement for RAG. They solve different problems: RAG is a retrieval pattern, MCP is a connection protocol that can carry a retrieval tool.
The night-before-the-interview bullets. Scan these on the way to the call.
Primary sources. Skim if you want the original framing.