Grok API Integration Rules (Developer Guide)

# Grok API Integration Rules

## Authentication
- API keys from console.x.ai
- Pass via Authorization header: Bearer xai-...
- Never expose keys in client-side code
- Use environment variables: XAI_API_KEY

## Model Selection
- grok-4-0709: Full capability, best reasoning
- grok-4-fast: Lower latency, production use
- grok-code-fast-1: Coding optimized (TS, Python, Java, Rust, C++, Go)
- grok-4.20-multi-agent: Multi-agent research coordination
- grok-4-1-fast-reasoning: Best tool-calling, 2M context

## API Compatibility
- OpenAI SDK compatible (base_url: https://api.x.ai/v1)
- Vercel AI SDK via @ai-sdk/xai
- LangChain via langchain-openai

## Tool Calling
- Built-in: web_search, x_search, code_execution, file_search
- Remote MCP: specify server URL
- Custom functions: define tools in request
- Grok invokes multiple tools in parallel

## Error Handling
- 429: Rate limited, exponential backoff
- 503: Service temporarily unavailable
- 400: Check request format
- 401: Verify API key