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MCP Host

TL;DR

An MCP host is the top-level application that runs the LLM and coordinates one or more MCP clients. Claude Desktop, Claude Code, Cursor, Windsurf, and VS Code Copilot are all MCP hosts. The host handles user interaction, prompt composition, and dispatches tool calls to the right client.

In depth

An MCP host is the AI application that a user interacts with. It owns the conversation, runs (or connects to) the LLM, and embeds one or more MCP clients to reach external capabilities. The host's responsibilities include: rendering the UI, managing conversation state, performing LLM inference, dispatching tool calls to the correct client, and enforcing user permissions.

Hosts typically support MCP server configuration via a JSON file. Claude Desktop uses `claude_desktop_config.json`, Claude Code uses `.claude.json`, Cursor uses `.cursor/mcp.json`. The file lists servers to spawn along with their commands, arguments, and environment variables.

Hosts also handle security-sensitive decisions: when an MCP server requests filesystem roots, the host prompts the user for approval. When a server wants to invoke the LLM (sampling), the host controls whether to allow it. The host is the trust boundary for the user.

Every popular AI coding tool in 2025 is an MCP host. The ecosystem is rapidly expanding to include custom-built hosts (internal company AI copilots) using the MCP host SDK.

Code example

// Claude Desktop / Claude Code config
{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": { "GITHUB_TOKEN": "ghp_..." }
    },
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/Users/me/projects"]
    }
  }
}

Examples

  • 1
    Claude Desktop — Anthropic's official MCP host app
  • 2
    Claude Code — CLI host for terminal-first AI coding
  • 3
    Cursor — AI-first IDE with built-in MCP support
  • 4
    Windsurf — Codeium's MCP-compatible IDE
  • 5
    VS Code with GitHub Copilot's MCP extension

What it's NOT

  • ✗A host is NOT an MCP server — it consumes, it doesn't provide.
  • ✗A host is NOT required to run the LLM locally — it can call remote APIs (OpenAI, Anthropic).
  • ✗A host is NOT limited to coding tools — any AI app (chat, analysis, agent) can be a host.
  • ✗A host does NOT directly execute tool calls — it delegates to the client, which talks to the server.

Related terms

Model Context Protocol (MCP)MCP ClientMCP ServerClaude DesktopCursor

See also

  • MCP Architecture
  • Anthropic Host List

Frequently asked questions

Can I build my own MCP host?

Yes — the MCP client SDKs let you embed client logic in any app. Combine with your LLM of choice and you have a custom host.

Where does the host config live?

Depends on the host: Claude Desktop uses `claude_desktop_config.json`, Claude Code uses `.claude.json`, Cursor uses `.cursor/mcp.json`.

Can multiple hosts share MCP servers?

Not directly — each host spawns its own subprocesses. But servers are stateless by default, so running the same server in multiple hosts is safe.

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