looking-up-docs（查找文档）

Documentation Lookup with Context7

Context7 provides up-to-date, version-specific documentation and code examples directly from source libraries.

Why Context7

• Current APIs: No hallucinated or outdated patterns
• Version-specific: Gets docs for exact library versions
• Code examples: Real, working code from actual documentation

Workflow

1. Resolve library ID: mcp__context7__resolve-library-id with libraryName
2. Get documentation: mcp__context7__query-docs with context7CompatibleLibraryID and topic

Modes

Examples

# React hooks
resolve-library-id: "react"
get-library-docs: context7CompatibleLibraryID="/facebook/react", topic="hooks", mode="code"

# Next.js middleware
resolve-library-id: "next.js"
get-library-docs: context7CompatibleLibraryID="/vercel/next.js", topic="middleware"

# Go net/http
resolve-library-id: "go net/http"
get-library-docs: context7CompatibleLibraryID="/golang/go", topic="http server"

# Kubernetes API
resolve-library-id: "kubernetes"
get-library-docs: context7CompatibleLibraryID="/kubernetes/kubernetes", topic="deployment"

Tips for Better Results

Be specific with queries:

• BAD: topic="hooks" → returns everything hook-related
• GOOD: topic="useEffect cleanup function" → precise results

Filter strategies:

• Use topic with function/method names: topic="json.Unmarshal"
• Include version when relevant: libraryName="react 18"
• Combine with feature context: topic="middleware error handling"

When results are too broad:

1. Narrow the topic parameter
2. Try mode="code" to focus on examples
3. Paginate: page=2, page=3 for additional results
4. Re-resolve library ID with more specific name

Quality check:

• Verify code examples match your library version
• Cross-reference with official docs if uncertain

Fallback: Empty or Missing Results

When Context7 returns no results or doesn't have the library:

Decision Tree

Context7 query returns empty?
├── Try broader query (e.g., "hooks" instead of "useCallback")
├── Still empty?
│   ├── Re-resolve library ID with alternative name
│   │   (e.g., "nextjs" → "next.js", "golang" → "go")
│   └── Still empty?
│       ├── Library not indexed → Use fallbacks below
│       └── Very niche library → WebSearch for official docs

Fallback Strategies

1. Alternative library ID: Try variations

   # If "fastapi" fails, try:
   resolve-library-id: "starlette"  # FastAPI's underlying framework
   resolve-library-id: "pydantic"   # Often used with FastAPI

1. WebSearch for official docs:

   WebSearch: "<library> official documentation <feature>"
   WebFetch: Official docs URL → extract relevant info

1. Source code exploration (for open-source):

   # Clone and explore
   git clone --depth=1 <repo>
   Grep: "function <name>" --type=<lang>

1. Perplexity for recent/niche libraries:

   mcp__perplexity-ask__perplexity_ask: "How to use <feature> in <library> 2024"

Libraries Commonly Not in Context7

Example Fallback Flow

# Initial attempt fails
resolve-library-id: "htmx"
→ No results

# Fallback 1: WebSearch
WebSearch: "htmx documentation hx-swap"
→ Found: https://htmx.org/docs/

# Fallback 2: Fetch docs
WebFetch: url="https://htmx.org/docs/", prompt="Explain hx-swap attribute"
→ Returns relevant documentation

When to Skip Context7 Entirely

• Asking about breaking changes between versions → WebSearch release notes
• Debugging specific error messages → WebSearch + StackOverflow
• Comparing libraries → Perplexity for analysis
• Very recent features → WebSearch for latest docs