MCP vs RAG vs AI Agents
To understand modern AI systems, you need to understand how these three pieces fit together.
๐ฅ๐๐ = โ๐๐ถ๐๐ฒ ๐๐ต๐ฒ ๐บ๐ผ๐ฑ๐ฒ๐น ๐ฏ๐ฒ๐๐๐ฒ๐ฟ ๐ฎ๐ป๐๐๐ฒ๐ฟ๐โ
RAG retrieves relevant data, injects it into the prompt, and generates a grounded response. Itโs best when your problem is answering questions using your docs, reducing hallucinations, or showing sources and citations. RAG improves what the model knows, not what it can do.
If youโre building with these patterns, here's a great guide on scaling multi-agent RAG systems:
lucode.co/multi-agent-rag-arโฆ
๐ ๐๐ฃ = โ๐ฆ๐๐ฎ๐ป๐ฑ๐ฎ๐ฟ๐ฑ๐ถ๐๐ฒ๐ฑ ๐๐ผ๐ผ๐น ๐ฎ๐ป๐ฑ ๐ฑ๐ฎ๐๐ฎ ๐ฎ๐ฐ๐ฐ๐ฒ๐๐โ
MCP is a standardized interface between LLMs and external systems like APIs, databases, and apps. Use it when your model needs to query data, call services, or interact with real systems (Slack, GitHub, etc). MCP doesnโt decide actions, it defines how tools are exposed.
๐๐ ๐๐ด๐ฒ๐ป๐๐ = โ๐ ๐ฎ๐ธ๐ฒ ๐๐ต๐ฒ ๐บ๐ผ๐ฑ๐ฒ๐น ๐๐ฎ๐ธ๐ฒ ๐ฎ๐ฐ๐๐ถ๐ผ๐ปโ
Agents operate in a loop: observe โ plan โ act โ repeat, often using tools and memory. Use them when your problem requires multi-step reasoning, tool usage with verification, or full task execution. Agents start where RAG stops, turning decisions into actions and outcomes.
The simple mental model:
RAG โ knowledge layer
MCP โ tool layer
Agents โ execution layer
Not every system needs all three explicitly, but complex ones often combine them.
If you want to see what this looks like in practice, this guide walks you through building a scalable multi-agent RAG system.
Check it out:
lucode.co/multi-agent-rag-guโฆ
What else would you add?
โป๏ธ Repost to help others learn AI.
๐ Thanks to
@Oracle for sponsoring this post.