Anthropic Python SDK

What it does

• Messages API with sync / async / streaming clients
• Built-in prompt caching via cache_control breakpoints
• Batch API for 50% off async workloads
• Token counting and cost estimation helpers
• Tool use with strict schema validation and tool_choice controls

When to use it

Best for Python services calling the Claude API directly, async backends doing batch processing, and notebooks / scripts that need streaming for UIs. Pairs naturally with FastAPI for serving, LangChain for orchestration, and any database for memory.

Getting started

pip install anthropic

Set ANTHROPIC_API_KEY (and optionally ANTHROPIC_BASE_URL for Bedrock / Vertex) before importing.

Things to know

The SDK tracks prompt caching version differences carefully — pinning to a major version is recommended in production. For long-running batch workloads, use the AsyncAnthropic client; the sync client can hold the event loop.