julianobarbosa/context7

Context7

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

Why Context7

| Benefit | Description | |---------|-------------| | Current APIs | No hallucinated or outdated patterns - documentation comes from actual sources | | Version-Specific | Gets docs for exact library versions you're using | | Code Examples | Real, working code extracted from actual documentation | | Broad Coverage | 1000+ libraries including React, Next.js, Vue, Go, Python, Kubernetes, etc. |

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

| Tool | Purpose | Short form (after bun link) | Long form | |------|---------|-------------------------------|-----------| | lookup | Resolve + query in one shot | c7-lookup <library> <query> | bun src/cli/lookup.ts <library> <query> | | resolve | Find Context7 library ID | c7-resolve <library> [query] | bun src/cli/resolve.ts <library> [query] | | query | Query docs by known ID | c7-query <library_id> <query> | bun src/cli/query.ts <library_id> <query> |

CLI Flags

All three CLIs accept the same flag set.

| Flag | Effect | |------|--------| | --json | Emit JSON on stdout; suppress decorative output. Pipe to jq. | | --quiet, -q | Suppress info/success logs (warn/error still print to stderr). | | --no-cache | Skip the 24h disk cache (~/.cache/context7/resolved.json) for this call. | | --clear-cache | Wipe the disk cache and exit. | | --timeout <ms> | HTTP timeout in milliseconds. Default 30000. | | --max-retries <n> | Retry budget for 429 Rate Limit responses (with Retry-After). Default 1. | | --api-key <key> | Override CONTEXT7_API_KEY env var. | | --version, -V | Print version and exit. | | --help, -h | Print usage and exit. |

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

| Library | Context7 ID | CLI Shortcut | |---------|-------------|--------------| | React | /facebook/react | react | | Next.js | /vercel/next.js | next.js, nextjs | | Vue | /vuejs/vue | vue | | Kubernetes | /kubernetes/kubernetes | kubernetes, k8s | | Go stdlib | /golang/go | go, golang | | Python | /python/cpython | python | | Node.js | /nodejs/node | node, nodejs | | TypeScript | /microsoft/typescript | typescript, ts | | Prisma | /prisma/prisma | prisma | | Tailwind | /tailwindlabs/tailwindcss | tailwind, tailwindcss |

Workflow Routing

| Workflow | Trigger | File | |----------|---------|------| | ResolveLibrary | "find library ID", "resolve library" | Workflows/ResolveLibrary.md | | QueryDocs | "lookup docs", "get documentation", "code examples" | Workflows/QueryDocs.md | | FullLookup | "help me with [library]", "how do I use [feature]" | Workflows/FullLookup.md |

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.

| Exit | Kind | Cause | Recovery | |------|------|-------|----------| | 3 | auth | 401 — bad or missing CONTEXT7_API_KEY | Set the env var from context7.com/dashboard or pass --api-key <key>. | | 4 | not_found | 404 — library or doc path missing; or malformed ID (missing leading /) | Run c7-resolve <name> to get a valid ID; check the /org/project shape. | | 5 | rate_limit | 429 — public rate limit hit; auto-retries once if Retry-After is present | Set CONTEXT7_API_KEY for higher limits, or raise --max-retries. | | 6 | server | 5xx — transient Context7 server error | Wait briefly and retry. | | 7 | timeout | 408 — request aborted by client timeout | Raise --timeout (e.g. --timeout 60000) or check network. | | 2 | (arg) | Unknown flag, bad value, missing required flag arg | Run --help. | | 1 | (other) | Anything else, including 0-status network errors | Check stderr message; retry. |

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

| Variable | Description | Default | |----------|-------------|---------| | CONTEXT7_API_KEY | API key for higher rate limits | None (uses public rate limits) |

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);
}