## Definition The **Model Context Protocol (MCP)** is an open standard introduced by Anthropic in November 2024 that lets an agent talk to external systems via a small set of standardised verbs (list resources, read a resource, call a tool). Donated to the Agentic AI Foundation under the Linux Foundation in December 2025. ## Core Primitives - **Tools** — callable functions exposed by the server. - **Resources** — readable data the server makes available. - **Prompts** — server-provided prompt templates. ## Transport JSON-RPC 2.0 messages over stdio or HTTP. A stateful conversation between client (e.g., Claude Code) and server (e.g., a Postgres MCP server). ## Why It Matters From the model's perspective, querying Jira looks identical to querying Postgres or filesystem. No fragmented per-tool shapes; uniform interface. ## Ecosystem (2026 snapshot) - 97M+ monthly SDK downloads. - 10,000+ active servers in production. - Hundreds of integrated AI clients. ## Extensions **MCP Apps** (SEP-1865, formalised early 2026) standardises delivery of interactive UIs — React-based dashboards, forms, data visualisations — from servers to host applications. ## Related - [[MCP Server]] - [[Extension Trifecta]] - [[Model Context Protocol Specification]]