Knowing the problem MCP solves tells you when to reach for it instead of writing one-off tool code.
You already know that a model can ask your code to run a function (tool calling). The catch is that every AI app wires those functions up in its own way. A GitHub integration written for one chat app has to be rewritten for an IDE, and again for your own agent.
Think of phone chargers before USB-C: every brand had its own plug. The Model Context Protocol (MCP) is the USB-C for AI apps. A protocol is just an agreed set of messages two programs exchange. MCP fixes those messages, so:
- a team writes an MCP server for their system (GitHub, a database, your company wiki) once,
- any app that speaks MCP (Claude, Claude Code, Cursor, VS Code, your own agent) can plug it in.
Without a standard, N apps and M systems need N times M integrations. With MCP they need N plus M.
MCP is open source. Anthropic published it in late 2024 and it is now governed in the open, with official SDKs (software development kits: libraries that implement the protocol for you) in Python, TypeScript, Go, C#, Java, Rust and more.
What MCP is not: it is not a model, not an agent framework, and it does not decide what the model does. It only standardizes how an app discovers what a server offers and calls it. The app and its model still decide when to use it.
The current specification (the official rulebook) is dated 2026-07-28. MCP names versions by the date of their last breaking change.
Remember
- MCP standardizes how AI apps talk to tools and data sources
- Write a server once, use it from any MCP-capable app
- It turns N x M custom integrations into N + M
- Versions are dates; the current spec is 2026-07-28
Watch out for
- Thinking MCP replaces tool calling. It builds on it: MCP is how the tools get to the app in a standard way.