12/06/2026
Most AI agent failures are context failures.
The source post breaks down the 3 context layers every serious AI agent needs.
MCP, RAG, and Skills are not interchangeable.
They solve different failure modes.
→ MCP solves the tool-access problem.
Without MCP, every Slack, Qdrant, or Brave Search connection can become custom API work.
With MCP, the agent uses a standardized protocol.
The basic flow:
User query → MCP Client → MCP Server → external tool → final response.
Use MCP when the agent needs to act across tools and services.
The diagnostic check:
If every new integration needs fresh code, you likely need MCP.
→ RAG solves the knowledge problem.
Without RAG, an LLM answers from training data and can hallucinate.
With RAG, the agent retrieves relevant information first.
The basic flow:
Data sources → chunking → embeddings → Vector DB → retrieval → LLM output.
Use RAG when the agent needs accurate answers from changing documents, databases, PDFs, or websites.
The diagnostic check:
If answers depend on private or dynamic knowledge, you likely need RAG.
→ Skills solve the repeatable-action problem.
Without Skills, you keep stuffing the same instructions into every prompt.
With Skills, the agent loads reusable actions only when needed.
The basic flow:
User request → Skill Manager → Skill Selection → Git, Docker, Python Interpreter, or Shell → result.
Use Skills when the agent needs repeatable workflows without repeated instructions.
The diagnostic check:
If prompts keep getting longer just to repeat process rules, you likely need Skills.
✅ MCP connects the agent to tools.
✅ RAG connects the agent to knowledge.
✅ Skills connect the agent to reusable actions.
The real mistake is treating “agent context” as one thing.
It is a stack.
Before building another agent, map the failure mode first.
If it cannot access tools, add MCP.
If it cannot trust answers, add RAG.
If it cannot repeat work, add Skills.
And weak context makes weak agents.
Which layer is your team missing right now?