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What is MCP (the Model Context Protocol)?

The open standard that lets an AI assistant use your tools and data — what a server exposes, how a connection works in the 2026-07-28 revision, and what MCP is not.

The Model Context Protocol (MCP) is an open standard for connecting an AI assistant to a system that holds your data. A program called an MCP server describes what it can do in a form the assistant can read, and the assistant calls those capabilities when they would help answer you. It is the difference between an assistant that can only talk about your work and one that can look things up and write them down.

Anthropic published MCP as an open specification, and it is not specific to Claude. The current revision is 2026-07-28, the fifth.

The problem it solves

An assistant on its own has no access to your systems. You can paste things in, but that is manual, it goes stale, and nothing you ask it to remember survives the conversation. The old fix was a custom integration per assistant per tool — an N×M problem nobody wanted to maintain.

MCP makes it N+M. A tool implements the protocol once and every compliant assistant can use it; an assistant implements it once and reaches every server.

What a server actually exposes

  • Tools — actions the model may invoke, each with a name and a schema for its arguments. Tools are model-controlled: the model decides when one is worth calling. A well-behaved client still asks you before anything is changed.
  • Resources — data the client can read and put in front of the model.
  • Prompts — reusable templates a user can pick deliberately.

Most servers you meet are mainly tools. Sambandh exposes 14 — five that read, five that only add, four that change or delete. Our tools reference lists them.

How a connection works now

This is where current documentation and older tutorials disagree, so it is worth being precise. In the 2026-07-28 revision MCP is stateless:

  • There is no initialize handshake. It was removed. Every request carries its own protocol version and client capabilities in a _meta field.
  • There are no protocol-level sessions, and the Mcp-Session-Id header is gone from the Streamable HTTP transport. A server needing state across calls mints an explicit handle and passes it as an ordinary tool argument.
  • Servers must implement server/discover, which reports the protocol versions, capabilities and identity a server supports. A client may call it first to pick a version.
  • A version the server will not accept returns UnsupportedProtocolVersionError rather than failing vaguely.

If a tutorial tells you to implement initialize and track a session id, it predates this revision. Code written that way can still be served through backward compatibility, but it is not what the current spec describes.

Remote servers and sign-in

A server can run on your own machine over STDIO, or remotely over HTTP. Remote servers are the ones you add by pasting a URL. Authorization is optional in the protocol, but an HTTP server holding private data should implement it, and the spec aligns it with ordinary OAuth 2.0 — you sign in to the service itself and grant the assistant access, so the assistant never holds your password.

Sambandh is a remote server at https://sambandh.ai/mcp, and signing in is an email one-time code. Nothing about that is special to us; it is the normal shape of a remote MCP server.

What MCP is not

  • Not a model. It is plumbing. The assistant still decides what to do.
  • Not a replacement for your API. A server usually sits in front of one, describing it in terms a model can use.
  • Not an agent framework. It defines how a client and a server talk, nothing more.
  • Not automatic safety. A server can expose destructive tools. Which ones run without asking is the client’s decision, and yours.

Trying one

In Claude on the web or desktop, custom connectors live under Customize › Connectors; you paste a server’s URL and sign in. In Claude Code you add one with claude mcp add. The steps for ours are in Connect Claude and Connect Claude Code, and the same shape applies to any server.

Two habits worth forming with any MCP server: read what a tool says it did rather than assuming, and keep “always allow” for tools that only add, so edits and deletes still stop to ask.

Where this is written down

The specification lives at modelcontextprotocol.io. This page summarises the 2026-07-28 revision as of October 2026; where it and the spec disagree, the spec is right.

Disclosure: Sambandh is an MCP server — a CRM for one person, used from Claude. We wrote this because we had to understand the protocol to build on it.