# MCP Spec

> Router skill for the Model Context Protocol (MCP) open spec, covering the protocol itself (JSON-RPC framing, capabilities, lifecycle), the client and server roles, the transport layers (stdio / streamable HTTP / SSE), and the core primitives (tools, resources, prompts, sampling, roots, completion). Use when the user asks about: writing an MCP server (in any language), writing an MCP client, the JSON-RPC protocol framing, the initialize handshake, capability negotiation, the stdio transport, the streamable HTTP transport, the SSE transport, defining a tool / resource / prompt, sampling, roots, or completion. Includes the TypeScript SDK (`@modelcontextprotocol/sdk`) and Python SDK (`mcp`). Skip: Anthropic's hosted MCP connector (use anthropic-platform-features), the user-facing Claude Connectors directory (use claude-connectors), Claude Code's `.mcp.json` config (use claude-code → SKILL-mcp).

- Skill: `xiaolai/mcp-spec` (Agent Skill, multi-file: 24 files)
- Install (CLI): `npx skillmds@latest add xiaolai/mcp-spec`
- Raw SKILL.md: https://api.skillmd.com/api/skills/xiaolai/mcp-spec/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: xiaolai (https://skillmd.com/u/xiaolai)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/xiaolai/mcp-spec

---


# Model Context Protocol (MCP) — Router

| Field | Value |
|---|---|
| **Source docs** | [modelcontextprotocol.io](https://modelcontextprotocol.io) |
| **Spec repo** | [modelcontextprotocol/modelcontextprotocol](https://github.com/modelcontextprotocol/modelcontextprotocol) |
| **TypeScript SDK** | [`@modelcontextprotocol/sdk`](https://www.npmjs.com/package/@modelcontextprotocol/sdk) |
| **Python SDK** | [`mcp`](https://pypi.org/project/mcp/) |

> **This skill is auto-updated daily.** A pipeline reads the upstream
> docs and rewrites the per-surface files below. Section structure is
> stable; content drifts to track upstream.

## Dispatch table

| Surface file | Read when the user asks about… |
|---|---|
| [`SKILL-protocol.md`](SKILL-protocol.md) | JSON-RPC framing, the `initialize` handshake, capability negotiation, lifecycle, error codes, versioning |
| [`SKILL-clients.md`](SKILL-clients.md) | implementing an MCP client, calling tools, reading resources, the client-side of sampling |
| [`SKILL-servers.md`](SKILL-servers.md) | implementing an MCP server in TypeScript or Python, server-side capability advertisement, server lifecycle |
| [`SKILL-transport.md`](SKILL-transport.md) | stdio transport, streamable HTTP transport, SSE transport (legacy), choosing a transport |
| [`SKILL-tools-resources-prompts.md`](SKILL-tools-resources-prompts.md) | defining tools (input schema, output schema), defining resources (URI templates, MIME types), defining prompts, sampling, roots, completion |

---

*This skill is auto-updated daily by a maintainer-run pipeline. File
issues at [xiaolai/anthropic-docs](https://github.com/xiaolai/anthropic-docs).*