Claude API Cheat Sheet — Python One-Liners & Patterns

## A Dense, No-Fluff Reference for Claude API Developers 40 most-reached-for Claude API patterns in a single printable page and a companion `.py` file you can run directly. ### What's Covered **Basic calls** — sync/async `messages.create`, streaming, token counting **Prompting patterns** — few-shot examples, structured output with XML tags, chain-of-thought forcing **Tool use** — defining schemas, parsing `tool_use` blocks, multi-turn tool loop skeleton **Cost control** — prompt caching setup (saves up to 90%), model aliases, batch API skeleton **Error handling** — rate limit retry with exponential backoff (one decorator), overload patterns ### Format - PDF (A4 + US Letter, print-optimized) - `.py` source file with every snippet runnable - Markdown version for Notion/Obsidian **Free. Tip if it saves you time.**