What is an MCP? A Plain-English Guide to the Model Context Protocol
MCP (Model Context Protocol) is the open standard for letting AI models talk to your tools and data. Here is what it is, why it matters, and how to try one in 30 seconds.
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If you've spent any time around AI tooling lately you've seen the letters MCP everywhere. Here's what it actually means, why it matters, and what it lets you do that you couldn't before.
MCP stands for Model Context Protocol. It's an open standard, originally published by Anthropic in late 2024, that defines how an AI model talks to outside tools and data. Think of it as a wall socket. Any model that speaks MCP can plug into any server that speaks MCP, and the two sides don't need to know anything else about each other.
Before MCP, every team that wanted to give Claude or GPT access to their database, their CRM, or their internal API had to build a custom integration. The model needed bespoke function definitions. The server needed bespoke auth. The schema drifted every time someone shipped a new endpoint. You ended up with a one-off bridge for every model-tool pair.
MCP collapses that into one contract. A server exposes three things:
- Tools: actions the model can call, like
create_invoiceorsearch_users - Resources: read-only data the model can pull, like a file or a database row
- Prompts: pre-written templates a user can invoke
Any MCP-compatible client (Claude Desktop, Cursor, ChatGPT, your own agent) can discover those capabilities at runtime and use them without you writing client-side glue.
Why people care
Three reasons:
- Reusability. Build an MCP server once, get every major AI product as a client for free.
- Portability. Your tools aren't locked to one model vendor.
- Discoverability. Models can list available tools and decide which to use, instead of you hardcoding function calls.
What it isn't
MCP is not a replacement for HTTP. Most MCP servers run over stdio for local clients or HTTP/SSE for remote ones. It's a protocol layer, not a network layer.
It's also not a way to skip auth. Each MCP server still has to enforce its own permissions. The protocol carries the message; you still own the security.
Try one in 30 seconds
The fastest way to see what an MCP actually does is to run one. PreMan ships with a public catalog of MCP servers you can hit from the browser. Pick one, click a tool, see the JSON come back. No install, no key, no terminal.
Bring the loop to your API
Catch the regression. Open a verified fix.
Join the waitlist to see which users a release may affect, monitor endpoints in production, and prepare a reviewable fix PR when something breaks.