What is MCP host?

An MCP host is the top-level application in a Model Context Protocol setup, the program a person opens and talks to. It contains the language model (or talks to one over an API) and embeds one or more MCP clients, each of which holds a connection to a server. The host's job is orchestration: it decides which servers to connect to, manages user permission for tool calls, gathers the tools and resources those servers expose, and presents them to the model so it can choose what to invoke. Familiar hosts include Claude Desktop, the Claude and ChatGPT apps, IDEs like Cursor, VS Code, and Zed, and agent frameworks. It helps to keep the three roles straight: the host is the app, the client is the per-server connection inside it, and the server is the external program providing capabilities. A single host can run many clients at once, which is how one chat window ends up with GitHub, a database, and a memory server all available in the same conversation.