- MCP (Model Context Protocol) is an open standard for connecting AI applications to external systems, like a shared socket for many plugs.
The MCP documentation compares the protocol to a USB-C port: one standard socket instead of a separate integration for every pair of application and service. The specification describes three roles: the host, that is the AI application, the client inside the host, and the server, which provides tools, resources and prompts. Communication relies on JSON-RPC 2.0 messages.
Caution
An MCP server is somebody else’s code with access to the data you expose to it, and its tool descriptions land in the model’s context. Before connecting assess the author, the code, the permissions and the data scope, as in the article How to add an MCP server to Claude Code.
Where to read next
An introduction: MCP in five minutes. The concepts agent and human in the loop. The whole topic: the MCP hub.