# Claude-api Skill: A Pocket Reference Manual for Claude API Developers

Anthropic's open-source claude-api Agent Skill packages the documentation of Messages API, Managed Agents and 8 programming language SDKs including Python, TypeScript and Go into progressively loadable references, which is built into Claude Code. This article introduces its positioning, core capabilities (model migration, streaming, tool calling, Prompt Caching, MCP/Agent), installation method and typical usage, helping developers avoid writing outdated Claude API code from memory.