Why MCP Is the New REST

A claim that gets thrown around too quickly. Here's the version of it that actually holds up.

The case

REST became the default API style because it picked one transport (HTTP), one shape (resources + verbs), and one schema language (eventually OpenAPI), and let everyone else stop arguing. The standardization was the win, not any specific elegance.

MCP is doing the same thing for AI tool use. Before MCP, every model vendor had its own tool format. Every AI app had its own way of registering integrations. Every server hosting tools had to ship N adapters. MCP collapsed that into one contract: tools, resources, prompts, over stdio or HTTP+SSE.

That's the parallel. It's not "MCP replaces REST." It's "MCP plays the role for AI clients that REST played for browsers."

Why it stuck where earlier attempts didn't

Earlier protocols for AI tool calling (plugins, custom GPT actions, vendor SDKs) all failed for the same reason: they were single-vendor. MCP is open, was adopted by Anthropic, OpenAI, and the major IDE vendors within twelve months, and works locally without a hosting story. That combination is what tipped it.

What it doesn't replace

• HTTP. Your servers still speak HTTP under MCP.
• REST endpoints for human apps. Your dashboard isn't going to use MCP to talk to its backend.
• API keys. MCP doesn't define an auth layer; it inherits one.

What it does change

• Where tool definitions live. Used to be inside each app; now in a server.
• Who builds integrations. Used to be the AI app vendor; now the API owner.
• How fast new AI products get useful. A new AI app with MCP support gets a thousand tools on day one.

The pragmatic prediction

In two years, "what's your MCP server" will be as routine a question as "what's your API base URL" is today. Companies that don't have one will look like companies in 2010 that didn't have a public REST API: not broken, but conspicuously behind.

Get ahead of it

Stand up an MCP server in front of your existing API. PreMan hosts MCP servers, lets you wire tools to your endpoints in the browser, and gives you a public URL to share. You can have one running by lunch.

→ Host your first MCP server in PreMan