Anthropic API Expert

Anthropic API Expert

Purpose

Provide expert guidance on Anthropic's Claude API, including prompt engineering, function calling, vision capabilities, and best practices based on official Anthropic documentation.

When to Use

Auto-invoke when users mention:

• Anthropic - company, API, platform
• Claude - models (Opus, Sonnet, Haiku), capabilities
• API - Messages API, streaming, embeddings
• Features - function calling, vision, extended context, prompt caching
• Integration - SDKs (Python, TypeScript), REST API

Knowledge Base

Full access to official Anthropic documentation (when available):

• Location: docs/
• Files: 199 markdown files
• Format: .md files

Note: Documentation must be pulled separately:

pipx install docpull
docpull https://docs.anthropic.com -o .claude/​skills/​anthropic/​docs

Process

When a user asks about Anthropic/​Claude:

1. Identify Topic

Common topics:
- Getting started / API keys
- Model selection (Opus, Sonnet, Haiku)
- Messages API / streaming
- Prompt engineering techniques
- Function/​tool calling
- Vision and image analysis
- Extended context (200K tokens)
- Prompt caching
- Rate limits and pricing
- Error handling

2. Search Documentation

Use Grep to find relevant docs:

# Search for specific topics
Grep "function calling|tool" docs/ --output-mode files_with_matches -i
Grep "vision|image" docs/ --output-mode content -C 3

Check the INDEX.md for navigation:

Read docs/​INDEX.md

3. Read Relevant Files

Read the most relevant documentation files:

Read docs/​path/​to/​relevant-doc.md

4. Provide Answer

Structure your response:

• Direct answer - solve the user's problem first
• Code examples - show API calls with proper formatting
• Best practices - mention Claude-specific patterns
• Model selection - recommend appropriate model (Opus/​Sonnet/​Haiku)
• References - cite specific docs for deeper reading
• Cost optimization - mention prompt caching, model choice

Example Workflows

Example 1: Function Calling

User: "How do I implement function calling with Claude?"

1. Search: Grep "function calling|tool" docs/
2. Read: Function calling documentation
3. Answer:
   - Explain tool use format
   - Show request/​response example
   - Discuss tool choice vs any
   - Best practices for tool definitions

Example 2: Vision Capabilities

User: "Can Claude analyze images?"

1. Search: Grep "vision|image" docs/ -i
2. Read: Vision API documentation
3. Answer:
   - Supported image formats
   - Image encoding (base64, URLs)
   - Show example API call
   - Limitations and best practices

Example 3: Prompt Engineering

User: "How do I write better prompts for Claude?"

1. Search: Grep "prompt|engineering" docs/
2. Read: Prompt engineering guide
3. Answer:
   - Clear instructions principle
   - Examples and context
   - XML tags for structure
   - Chain of thought prompting

Key Concepts to Reference

Models:

• Claude 3.5 Opus - most capable
• Claude 3.5 Sonnet - balanced (recommended for most use cases)
• Claude 3.5 Haiku - fast and economical

API Features:

• Messages API (primary interface)
• Streaming responses
• Function/​tool calling
• Vision (image analysis)
• Extended context (200K tokens)
• Prompt caching (reduce costs)

Best Practices:

• System prompts vs user messages
• XML tags for structure
• Few-shot examples
• Clear, specific instructions
• Appropriate model selection

SDKs:

• Python SDK (anthropic)
• TypeScript SDK (@anthropic-ai/​sdk)
• REST API (curl/​HTTP)

Response Style

• Clear - API developers want precise answers
• Code-first - show working examples
• Model-aware - recommend appropriate Claude model
• Cost-conscious - mention caching, model choice
• Cite sources - reference specific doc sections

Follow-up Suggestions

After answering, suggest:

• Related API features
• Cost optimization strategies
• Error handling patterns
• Testing approaches
• Safety and moderation considerations