Context7 Documentation Lookup

Use the Context7 MCP tools to fetch accurate, up-to-date documentation for any library.

Process

Step 1: Resolve Library ID

First, find the Context7-compatible library ID:

Use tool: mcp__plugin_context7_context7__resolve-library-id
Parameter: libraryName = "<library name>"

Examples:

• For tokio: libraryName = "tokio"
• For serde: libraryName = "serde"
• For React: libraryName = "react"
• For Express: libraryName = "express"

Step 2: Fetch Documentation

After getting the library ID, fetch documentation:

Use tool: mcp__plugin_context7_context7__get-library-docs
Parameters:
  - context7CompatibleLibraryID = "<id from step 1>"
  - topic = "<specific topic>" (optional)
  - mode = "code" or "info"

Modes:

• code (default): API references, code examples, function signatures
• info: Conceptual guides, architecture, narrative documentation

Step 3: Paginate if Needed

If documentation is incomplete, fetch more pages:

Use tool: mcp__plugin_context7_context7__get-library-docs
Parameters:
  - context7CompatibleLibraryID = "<same id>"
  - topic = "<same topic>"
  - page = 2  (or 3, 4, etc.)

Common Lookup Patterns

Rust Crates

# Tokio async runtime
resolve-library-id: "tokio"
get-library-docs: topic="spawn", mode="code"

# Serde serialization
resolve-library-id: "serde"
get-library-docs: topic="derive", mode="code"

# Axum web framework
resolve-library-id: "axum"
get-library-docs: topic="routing", mode="code"

# sqlx database
resolve-library-id: "sqlx"
get-library-docs: topic="query", mode="code"

Understanding Concepts

# Learn about Tokio architecture
get-library-docs: topic="runtime", mode="info"

# Understand serde data model
get-library-docs: topic="data model", mode="info"

Specific APIs

# Tokio channels
get-library-docs: topic="mpsc channel", mode="code"

# Axum extractors
get-library-docs: topic="extractor", mode="code"

# tracing spans
get-library-docs: topic="span", mode="code"

When to Use Context7

Always use for:

• Looking up API details for external crates
• Finding correct function signatures
• Getting usage examples
• Understanding library patterns
• Checking latest API changes

Use mode="code" when:

• Need function signatures
• Want code examples
• Looking for API reference
• Implementing features

Use mode="info" when:

• Understanding architecture
• Learning concepts
• Reading guides
• Design decisions

Integration with Development

Before Implementation

1. Resolve library ID for relevant crates
2. Fetch documentation for the specific API you'll use
3. Check examples for correct usage patterns

During Debugging

1. Fetch docs for error types
2. Look up correct parameter types
3. Find working examples

Example Workflow

Task: Implement async HTTP client with reqwest

1. resolve-library-id: "reqwest"
   -> Returns: "/seanmonstar/reqwest"

2. get-library-docs:
   context7CompatibleLibraryID: "/seanmonstar/reqwest"
   topic: "client"
   mode: "code"
   -> Returns: Client builder patterns, request methods

3. get-library-docs:
   context7CompatibleLibraryID: "/seanmonstar/reqwest"
   topic: "error handling"
   mode: "code"
   -> Returns: Error types, retry patterns

Tips

• Be specific with topics for better results
• Use page parameter if first page doesn't have what you need
• Combine mode="info" for understanding + mode="code" for implementation
• Cache library IDs mentally for frequently used crates
• Check multiple topics if needed (e.g., "client" then "request builder")

Common Rust Ecosystem Lookups