What for: feeds AI up-to-date library documentation straight into the context, so it stops hallucinating APIs and outdated signatures.

What it gives the AI

The AI stops making up APIs. Context7 pulls current documentation and code examples for a specific version of a library in real time and drops them into the context. The model was trained on a snapshot of the past — it remembers deprecated signatures and invents methods that don't exist. Context7 fixes that.

Example: you ask for "middleware in Next.js 15 App Router". Without Context7 the AI writes code for Next 13 and the old pages/. With Context7 it first pulls the docs for version 15 and writes something that actually works.

Setup (exact steps)

Claude Code

A local stdio server via npx:

claude mcp add context7 -- npx -y @upstash/context7-mcp

An Upstash key is optional (higher limits, private sources) — it's passed as a server flag after --:

claude mcp add context7 -- npx -y @upstash/context7-mcp --api-key YOUR_KEY

There's also a hosted option (no local npx): claude mcp add --transport http context7 https://mcp.context7.com/mcp.

Cursor / Claude Desktop

In .cursor/mcp.json (per project) or ~/.cursor/mcp.json (global); for Claude Desktop, the same block goes into claude_desktop_config.json:

{
  "mcpServers": {
    "context7": {
      "command": "npx",
      "args": ["-y", "@upstash/context7-mcp"]
    }
  }
}

Usage example

Tell the AI: "use context7 — write a Drizzle ORM schema for the orders table". It calls resolve-library-id → get-library-docs, pulls fresh Drizzle docs and generates the schema in the current syntax rather than from year-old memory.

Security

Read-only by nature: the server only reads public documentation, it writes nothing into your project.
Supply chain: the @upstash/context7-mcp package comes from Upstash (★56.5k) — before installing, double-check you're getting that one and not a typosquatting clone.
The Upstash token is only needed for higher limits; basic usage requires no key.

Gotchas

Without a key you're on the public rate limits — heavy use will hit them; grab a free Upstash key.
It doesn't cover every niche library: if a repository isn't in the Context7 index, there are no docs to pull.
You have to write "use context7" in the prompt explicitly (or add a project rule) — it doesn't fire on every request by itself.