MCP
Also called: Model Context Protocol
MCP (Model Context Protocol) is an open standard that lets AI applications connect to external tools, data, and prompts through one consistent interface instead of a custom integration for each.
Before MCP, every AI application that wanted to give a model access to a tool — a database, a file system, a search API — had to write its own custom integration code for that specific combination of app and tool. MCP standardizes that connection so a tool only needs to be wired up once, as an MCP server, and any MCP-compatible application can use it.
MCP was originated by Anthropic and released as an open standard, with its specification published and since moved toward broader, community-driven governance. It has become the most widely referenced open standard for connecting AI applications to external context and capabilities, though the space is still actively evolving and other approaches exist alongside it.
In MCP's architecture, a host application (like a coding agent or chat client) runs an MCP client, which opens a connection to one or more MCP servers. Each server can expose three kinds of primitives: tools the model can call, resources it can read for context, and prompt templates it can reuse. The host decides what the model is allowed to see and invoke.
How it works
MCP communication runs over JSON-RPC 2.0, typically over stdio for local servers or HTTP-based transports for remote ones. When a client connects, it asks the server what it supports — a capability negotiation step — and the server responds with its available tools, resources, and prompts. From then on, the model (via the host) can call a tool with structured arguments, request a resource by its URI, or fetch a prompt template, and the server returns a structured result. Because the protocol is the same regardless of what the server actually does behind the scenes, a single MCP client implementation can talk to a filesystem server, a database server, and a project-management server without any server-specific code in the host application.
Example
A coding agent with an MCP client might connect to a github MCP server to open issues, a postgres MCP server to query a database, and a filesystem MCP server to read local files — all through the same protocol, with the model deciding at runtime which tool to call for a given step.
How it differs
MCP is sometimes confused with plain function/tool calling. Function calling is the underlying mechanism a model uses to invoke a structured call — MCP standardizes how that call, along with resources and prompts, gets exposed and discovered across many different tools and applications, so the model doesn't need a bespoke integration for each one.
Common misconceptions
FAQ
What is MCP used for?
Is MCP only for Claude?
Do I need to build my own MCP server?
Last checked: 2026-08-28