Which statement describes an MCP Host?

In the Model Context Protocol (MCP) architecture, the MCP Host is the central application—such as an AI Desktop app, IDE, or Agentic framework—that orchestrates user interactions, manages the core Large Language Model (LLM), and maintains connection lifetimes with various MCP clients. The Host acts as the primary runtime container, routing user prompts to the LLM and initiating client connections to external MCP servers. When the LLM decides to perform an action or retrieve context, the MCP Host facilitates communication through the appropriate MCP client connection, collects the result, and feeds it back into the model context to complete complex agentic tasks efficiently and securely.

A: The protocol specification document itself defines communication message formats and JSON-RPC schemas, not the MCP Host runtime component. B: The external REST API represents the target service or backend utility, which is wrapped and exposed by an MCP Server rather than the Host. C: Tool execution logic resides on and is executed directly by the MCP Server, whereas the Host coordinates connection lifecycle and context routing.

1. Model Context Protocol Specification, "MCP Architecture & Protocol Overview: Hosts, Clients, and Servers", https://spec.modelcontextprotocol.io/specification/architecture/

2. Anthropic Documentation, "Model Context Protocol (MCP) Core Concepts", 2024.