AI Agents, Tools, MCP, and Skills: The Core, The Embellishment, and The Gimmick

If you frequently read AI-related news or are currently looking into how to build an AI agent from scratch, you’ve definitely heard these terms: Agent, Tools, MCP (Model Context Protocol), and Skills. Marketing press releases from big tech and hype-chasing influencers will make you believe that if you just slap these four things together, AI will automatically take over your company’s entire operation, print money for you, and practically make you the CEO. But as a full-stack engineer with actual project experience, I can honestly tell you: take that hype with a grain of salt.