Context7

What it does

• resolve-library-id: name → resolved Context7 library ID (handles naming collisions)
• get-library-docs: pulls version-pinned docs + code examples for any library ID
• Topic filtering: narrow to a specific library feature (hooks, routing, etc.)
• Live, version-accurate — fetches at request time, no training-data drift
• Free public server (no API key) plus paid plan for higher rate limits
• Index covers tens of thousands of libraries (React, Next.js, Tailwind, Anthropic SDKs, MCP SDKs, and more) — see context7.com for the current list

When to use it

Best for Claude Code sessions where the model is hallucinating library APIs or citing outdated patterns. Add it to .mcp.json and Claude can pull current docs for React, Next.js, Tailwind, Anthropic SDKs, MCP SDKs, and many other libraries on Context7's index.

Getting started

npx -y @upstash/context7-mcp

Add to .mcp.json under mcpServers.context7 with no env required for the public server. Optional: set CONTEXT7_API_KEY for higher rate limits.

Things to know

Public server is rate-limited — heavy use in CI may need a paid plan or self-hosted deployment. Some niche libraries are not yet indexed; check the Context7 website before assuming coverage. Docs are fetched at request time, so first invocation has higher latency than cached alternatives.