We follow Alice, a developer at Acme Corp, to demonstrate how missing any of these layers leads to multi-platform integration headaches and expensive $18,000 security flaws.
🧠 WHAT YOU'LL LEARN:
- Why AI tools act as the "hands" that allow models to produce structured intent and call functions
- How Model Context Protocol (MCP) acts as the "USB-C for AI," decoupling tools from specific client implementations
- How AI Skills provide the "brain" and recipes to enforce business logic, judgment, and guardrails
- Security risks across each layer—from prompt injection and tool poisoning to missing human-in-the-loop controls
- How to implement OAuth 2.1 authorization and scoping for secure remote MCP servers
🛠️ RESOURCES & LINKS:
If you enjoy this content and want to learn more about identity, security, and access management, subscribe to our channel!
Have a topic you'd like to see covered? Let us know if the comments below 👀
Top comments (3)
"USB-C for AI" is the best analogy I've seen for MCP. But the article's real meat is the layering — most teams I've seen implement one of these (usually tools) and assume the other two are automatic.
The $18k flaw example is the part I'd want to see expanded: which specific layer failed? Because if the agent had a Skill with a guardrail that said "don't send money without human approval" but the MCP tool itself didn't enforce it, that's a Skill-layer failure. If the MCP server didn't enforce scope, that's an MCP-layer failure. The cost is the same, the fix is different.
Curious — in your Alice scenario, which layer was the actual breach point, or was it a combination?
I would say it was a combination.
Actually, you can't only rely on a skill saying "don't send money without human approval". The MCP tool must enforce this too.
It's the same pattern for classic client-server development: input validation at client side is not enough. The server must validate input as well.
Exactly. A "skill" (or system prompt) is just a polite suggestion to the LLM; it can be jailbroken, prompt-injected, or simply ignored. The MCP server, however, is the actual execution layer.
If the MCP tool physically requires a valid human_approval_token payload before it executes a transfer_funds() call, no amount of prompt engineering can bypass it. It's the exact same reason we don't rely on client-side JavaScript validation for bank transfers—the server must be the final gatekeeper.