What Is MCP Protocol?

MCP — Model Context Protocol — is the open standard for connecting AI assistants to tools and data sources. Anthropic launched it in late 2024; by 2026 it’s supported by Claude, ChatGPT, Cursor, Zed, Goose, and a growing list. Think of it as USB-C for AI integrations.

The problem MCP solves

Pre-MCP, every AI tool had its own way to integrate with external systems. Cursor extensions, ChatGPT custom actions, Claude tools — all incompatible. MCP defines a common protocol, so a server you write once works everywhere. The Slack MCP server you set up for Claude Desktop also works in Cursor, Zed, ChatGPT, etc.

How it works

An MCP server exposes resources (read-only data), tools (callable functions), and prompts(templates). The AI client connects to the server over JSON-RPC (stdio for local, HTTP/SSE for remote) and discovers what’s available. Authentication is handled by the server.

Servers worth knowing in 2026

• Filesystem, GitHub, Git, SQLite, Postgres, Slack — the official servers.
• Linear, Notion, Stripe, Google Drive — vendor-published.
• Brave Search, Fetch, Puppeteer — web access.
• Memory, Sequential Thinking — cognitive enhancements.

For setup recommendations by workflow, use the MCP server picker. For agent design overall, see best AI for agents.