Model Context Protocol (MCP)

Model Context Protocol (MCP): A JSON-RPC 2.0 protocol in which hosts run clients that connect to servers offering tools, resources and prompts. Example: The current revision is dated 2026-07-28 and its schema lives at schema/2026-07-28/schema.ts. Also in the glossary is mcp-publisher: The CLI that publishes a server.json to the official registry after namespace verification.

Definition

A JSON-RPC 2.0 protocol in which hosts run clients that connect to servers offering tools, resources and prompts.

Example, with source

The current revision is dated 2026-07-28 and its schema lives at schema/2026-07-28/schema.ts. (modelcontextprotocol.io, read 4 November 2026)

Where it appears on this site

• MCP
• Tool descriptions and agent success

Neighbouring terms

• mcp-publisher: The CLI that publishes a server.json to the official registry after namespace verification.
• Multi round-trip request (MRTR): The 2026-07-28 pattern where a server returns input_required and the client retries the request with the answers.
• Namespace verification: Proof that a publisher controls a registry name, by GitHub login or OIDC for io.github names and DNS or HTTP for domains.