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MCP Glossary

Model Context Protocol (MCP)

TL;DR

The Model Context Protocol (MCP) is an open standard introduced by Anthropic in November 2024 that lets AI applications connect to external tools, data sources, and systems through a unified interface. It uses JSON-RPC 2.0 and standardizes how LLMs call tools, fetch resources, and use prompts.

In depth

The Model Context Protocol (MCP) is an open protocol specification that standardizes how AI applications (clients) connect to external capabilities (servers). Instead of every AI tool implementing a custom integration for every service, MCP defines one protocol that any LLM client and any service can speak.

MCP separates three concepts: tools (functions the AI can call), resources (data the AI can read), and prompts (reusable templates). Communication happens over JSON-RPC 2.0, transported via stdio (local), Server-Sent Events, or streamable HTTP.

The protocol was designed by Anthropic and released as open source in November 2024. It is now adopted by Claude Desktop, Claude Code, Cursor, Windsurf, VS Code Copilot, and hundreds of third-party clients. MCP is often described as 'USB-C for AI' because it turns bespoke integrations into plug-and-play components.

MCP is language-agnostic — SDKs exist for TypeScript, Python, Rust, Kotlin, C#, and more. You can build an MCP server in any language that can speak JSON-RPC.

Code example

// Configure an MCP server in .claude.json
{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/allowed/dir"]
    }
  }
}

Examples

  • 1
    Claude Desktop using the filesystem MCP to read your local files
  • 2
    Cursor calling a GitHub MCP to open a PR automatically
  • 3
    A custom agent calling Stripe's official MCP to refund a customer
  • 4
    Perplexity's search MCP feeding fresh web data into any LLM
  • 5
    MCPizy distributing 300+ MCP servers for one-click install

What it's NOT

  • ✗MCP is NOT a new AI model — it's a protocol that lets any model talk to any tool.
  • ✗MCP is NOT proprietary to Anthropic — it's fully open source (MIT license) with broad ecosystem adoption.
  • ✗MCP is NOT a replacement for APIs — it's a standardized wrapper that makes any API LLM-accessible.
  • ✗MCP is NOT a framework like LangChain — it's a wire-level protocol, simpler and lower in the stack.

Related terms

MCP ServerMCP ClientMCP HostJSON-RPC 2.0MCP Tool

See also

  • Official MCP Site
  • Anthropic MCP Docs
  • MCP GitHub Org

Frequently asked questions

When was MCP released?

Anthropic open-sourced MCP on November 25, 2024, alongside the Claude Desktop launch.

Is MCP free to use?

Yes. The protocol and all official SDKs are open source under the MIT license.

What problem does MCP solve?

The N×M integration problem: before MCP, N AI apps × M tools meant N×M custom integrations. MCP reduces it to N + M.

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