What is MCP? The plain-English guide

MCP is how AI assistants plug into the apps you use. Here's what it is, why it matters, and how to tell if it works.

The one-sentence version

MCP (Model Context Protocol) is a universal plug that lets AI assistants like Claude, ChatGPT and Cursor use other apps: read your CRM, file a ticket, send an invoice, search the web.

Why it matters

Before MCP, every AI app had to build every integration itself. Now an app ships one MCP server and every AI assistant that speaks MCP can use it. That's why the ecosystem went from a handful of servers to 44,608 in the official registry.

Servers, tools, clients

Server: the thing an app publishes (for example, a Stripe or Notion MCP server).
Tools: the individual actions a server exposes, like create_invoice or search_pages. We list every tool we can verify live.
Client: your AI app (Claude, ChatGPT, Cursor, VS Code).

The catch nobody talks about

Listing a server is easy. Keeping it working is hard. At our last sweep only 84% of public remote endpoints answered a correct MCP handshake. That's why every page here shows live status, not just a description.

How to use this site

Start from an app on Apps to see if there's an official server.
Search by action on Tool search when you know what you want done, not which brand does it.
Watch the servers you rely on and get alerts on Changes.