This repository is the official Model Context Protocol (MCP) reference implementation, containing seven standalone servers (everything, filesystem, memory, sequentialthinking, fetch, git, time) written in TypeScript or Python. These servers demonstrate the full MCP protocol—tools, prompts, resources, transports (stdio, SSE, Streamable HTTP), subscriptions, sampling, elicitation, tasks, and structured content. They are designed as educational examples for developers building their own MCP servers, not as production-ready solutions. The codebase is well-structured with consistent patterns (server factory, transport abstraction, security-focused path validation, atomic file operations, knowledge graph management) and includes extensive test suites. While actively maintained, some Python servers show drift from the latest MCP SDK (v2 API renames in progress), and the Everything server's demo code is tightly coupled to experimental protocol features. The repository also serves as a central hub for the MCP ecosystem via a curated community resource directory (ADDITIONAL.md).