The model's knowledge stops at its training date, so it writes code for last year's API. Context7, built by Upstash, fetches the current docs for the exact library and version you use and puts them into the agent's context.
It has only two tools: find the library, then query its docs. That keeps it light on context, so it's an easy server to leave on all the time. Together with Playwright, it's the first server most developers should install.
A real run
We asked how to connect to a remote MCP server with the Vercel AI SDK. Context7 found v7.0.0 and caught three changes that would break code written from memory: a new package, a new transport option and a new step-limit API.
Watch out
- The agent often won't call it unless you say "use context7" or add a rule to
CLAUDE.md.
- Without an API key you hit lower rate limits. The key is free.
Install
Terminal
Loading editor...
claude mcp add --transport http context7 https://mcp.context7.com/mcp
Cursor, Codex and other clients take the same URL. For higher rate limits, get a free API key at context7.com/dashboard and pass it as an
Authorization: Bearer YOUR_API_KEY header.More in Top MCP servers for development.
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