julianobarbosa/claude-code-skills/context7

Context7

Query up-to-date, version-specific documentation and code examples directly from source libraries via Context7's documentation aggregation platform.

Why Context7

Setup

# Install dependencies
cd ~/.claude/skills/context7/Tools
bun install
 
# Optional: link binaries globally so c7-lookup / c7-resolve / c7-query are on PATH
bun link
 
# Optional: API key for higher rate limits
export CONTEXT7_API_KEY="ctx7sk_your_key_here"   # context7.com/dashboard

Available CLI Tools

CLI Flags

All three CLIs accept the same flag set.

Quick Reference

Full Lookup (Recommended)

One command to resolve library and query documentation:

# After `bun link`:
c7-lookup react "useEffect cleanup function"
c7-lookup next.js "app router middleware"
c7-lookup kubernetes "deployment rolling update"
 
# Or without linking:
cd ~/.claude/skills/context7/Tools && bun src/cli/lookup.ts react "useEffect cleanup function"

JSON output (for scripting / piping)

c7-lookup react "useState" --json | jq '.libraryId'
c7-resolve drizzle "many to many" --json | jq '.bestMatch'

Step-by-Step (when needed)

c7-resolve react                                    # → /facebook/react
c7-resolve next.js "authentication"                 # → ranked candidates
c7-query /facebook/react "useEffect cleanup"        # → docs for known ID

Common Library IDs

Workflow Routing

Gotchas

These are real Context7 API behaviors that bite if you don't know about them. Add to this list whenever a query goes wrong in a way that wasn't already documented.

1. Library ID requires a leading slash. /facebook/react works; facebook/react fails with a cryptic "library not found." The error doesn't tell you the slash is missing.
2. The resolver is fuzzy and ranked, not deterministic. resolve.ts <name> returns multiple candidates ordered by an LLM-powered ranker that takes your optional context query into account. A narrow context can promote a less-canonical fork above the official repo. Always inspect the top match before passing the ID to query.ts.
3. Version pinning matters at major boundaries. Library IDs may include a version segment: /vercel/next.js/14.2.0. The bare ID resolves to whatever Context7 currently treats as "latest stable," which can lag behind real releases — asking about Next.js "app router" without a pin can return Next 13 docs. Pin the version when the framework changed shape across majors.
4. Public rate limits are tight. Without CONTEXT7_API_KEY, you'll hit limits in fewer queries than you expect. The "max 3 calls per question" tip in this skill is a defensive ceiling on Claude's behavior — it is not the real API budget. Set the API key from context7.com/dashboard for any sustained use.
5. Snippet truncation is silent. Long doc pages return excerpts, not full content. If a returned example references a function or symbol the snippet didn't define, do NOT guess what it does — re-query with a tighter, more specific question rather than fabricating the missing piece.
6. The known-IDs cache can go stale. Common libraries (react, next.js, kubernetes, etc.) shortcut to hardcoded IDs in Tools/src/lib/context7.ts and skip the resolver entirely. If an upstream project renames its repo or moves orgs, the cached ID becomes wrong and queries silently miss. To force a fresh resolve, use an alias the cache doesn't know or pass --no-cache.

Common Errors

The CLIs use typed exit codes so callers (Claude included) can distinguish failure categories without parsing strings.

Errors always print Error: <message> and a Hint: <remediation> line to stderr. With --json, stdout stays clean and parseable; stderr keeps the human-readable error.

Examples

Example 1: React Hooks Documentation

cd ~/.claude/skills/context7/Tools
bun src/cli/lookup.ts react "useEffect cleanup function"

Output includes current React docs with cleanup pattern examples.

Example 2: Kubernetes Deployment Spec

bun src/cli/lookup.ts kubernetes "deployment spec rolling update strategy"

Output includes current K8s API reference for Deployment.

Example 3: Next.js App Router

bun src/cli/lookup.ts next.js "middleware authentication app router"

Output includes latest Next.js middleware documentation.

Example 4: Using in Claude Code Session

When you need documentation during a coding session:

User: "How do I implement server-side data fetching in Next.js 14?"
 
Claude runs:
  cd ~/.claude/skills/context7/Tools && bun src/cli/lookup.ts next.js "server components data fetching"
 
Then synthesizes response with current patterns (Server Components, not old getServerSideProps)

Environment Variables

Get your API key at context7.com/dashboard

Tips

• Be specific in your query for better results
• Max 3 calls per question - if you can't find it after 3 tries, use best available info
• Include version in query if you need specific version docs (e.g., "React 18 concurrent features")
• Combine with local context - use Context7 to verify APIs, then apply to your codebase
• Known IDs skip API - common libraries like react, next.js use cached IDs to skip the resolve step

Project Structure

Tools/
├── package.json              # Bun + bin entries (c7-resolve, c7-query, c7-lookup)
├── tsconfig.json             # TypeScript strict config
├── src/
│   ├── index.ts              # Public exports (client, types, helpers)
│   ├── lib/
│   │   ├── context7.ts       # Core API client + retry + typed errors
│   │   ├── cache.ts          # Disk cache for resolved library IDs (24h TTL)
│   │   ├── flags.ts          # Shared CLI argument parser
│   │   └── errors.ts         # Error → exit-code + hint formatter
│   └── cli/
│       ├── lookup.ts         # Full lookup command (c7-lookup)
│       ├── resolve.ts        # Library ID resolver (c7-resolve)
│       └── query.ts          # Documentation query (c7-query)
└── tests/
    ├── cache.test.ts         # Cache I/O + TTL roundtrips
    ├── flags.test.ts         # Argument parsing edge cases
    └── errors.test.ts        # Exit code + hint mapping

API Reference

The TypeScript client can also be imported programmatically:

import {
  Context7Client,
  getKnownLibraryId,
  setLogLevel,
  formatError,
  getCached,
  setCached,
} from "./src/index.js";
setLogLevel("warn"); // silence info/success logs
const client = new Context7Client({
  apiKey: process.env.CONTEXT7_API_KEY,
  timeout: 30_000,
  maxRetries: 2,
});
// Full lookup with disk cache
const cached = await getCached("react", 24 * 60 * 60 * 1000);
if (cached) {
  const docs = await client.queryDocs(cached, "useEffect cleanup");
  console.log(docs.rawContent);
} else {
  const result = await client.lookup("react", "useEffect hooks");
  if (result.library) await setCached("react", result.library.id);
  console.log(result.rawContent);
}