context7

Context7 MCP Usage Guide

Context7 provides current library documentation to prevent hallucinated APIs. It exposes two tools that must be used in sequence.

Core Workflow

Step 1: Resolve the library ID

resolve-library-id(libraryName: "next.js")
→ Returns: /vercel/next.js (plus metadata, trust scores, versions)

Step 2: Fetch documentation

query-docs(
  context7CompatibleLibraryID: "/vercel/next.js",
  topic: "middleware",  // optional — focuses results
  tokens: 5000          // optional — default 5000, min 1000
)

Skip Step 1 only when the exact library ID is already known from a previous call or user input.

Library ID Format

Format	Example	Use Case
/org/project	/vercel/next.js	Latest docs
/org/project/vX.Y.Z	/vercel/next.js/v15.1.0	Version-specific

Note the v prefix on version numbers.

When to Use Context7

Activate for:

• Libraries released or updated after training cutoff (Next.js 15, React 19, Svelte 5)
• Fast-evolving frameworks (TanStack Query, Tailwind CSS, Zod, Prisma)
• Setup and configuration tasks requiring current syntax
• Version-specific API questions
• Niche libraries with limited training data

Skip for:

• Vanilla JavaScript, HTML, CSS
• General algorithms and data structures
• Stable, well-documented APIs (lodash basics, moment.js)
• Non-code tasks

Using the Topic Parameter

Focus documentation retrieval with specific topics:

query-docs(
  context7CompatibleLibraryID: "/supabase/supabase-js",
  topic: "authentication"  // Much better than fetching all docs
)

Good topic values: routing, hooks, authentication, middleware, configuration, testing, deployment, database, api, components

Error Handling

See references/error-handling.md for common errors and solutions.

Quick reference:

• "Documentation not found" — Library may not be indexed; check context7.com or try base ID without version
• Empty results — Try broader topic or remove topic parameter
• Rate limit errors — Back off and retry; consider API key for heavy usage

High-Value Libraries

These benefit most from Context7 (fast-changing APIs):

Category	Libraries
React ecosystem	Next.js, React, TanStack Query, Zustand
CSS/Styling	Tailwind CSS, Panda CSS, StyleX
Validation	Zod, Valibot, ArkType
Database/ORM	Prisma, Drizzle, Supabase
Full-stack	Nuxt, SvelteKit, Astro, Remix