MCP — Model Context Protocol

The Model Context Protocol standardises how an AI application discovers and calls external capabilities, turning N × M bespoke integrations into N + M.

An MCP server exposes tools (model-invoked actions), resources (application-read data) and prompts (user-selected templates); knowing which is which decides who controls the call.

A session runs initialise → capability negotiation → listing → invocation over a transport such as stdio or streamable HTTP, with auth and error handling at each step.

Direct API code is tightest and fastest, function calling adds model-driven invocation, MCP adds discovery and reuse across applications — each wins in a different N × M regime.