claude-code-sdk

# Claude Code SDK

Authoritative reference for Claude Code extensibility and configuration.

## Route to Reference

| Working with | Reference |
|--------------|-----------|
| Skills: SKILL.md, frontmatter, activation, subagent execution | [skills.md](references/skills.md) |
| Subagents: custom agents, tool restrictions, delegation | [subagents.md](references/subagents.md) |
| Plugins: plugin.json, directory structure, distribution | [plugins.md](references/plugins.md) |
| Hooks: lifecycle events, command/prompt/agent hooks | [hooks.md](references/hooks.md) |
| MCP: servers, tools, resources, authentication | [mcp.md](references/mcp.md) |
| Memory: CLAUDE.md, rules, imports, hierarchy | [memory.md](references/memory.md) |
| Output Styles: personas, system prompt modification | [output-styles.md](references/output-styles.md) |
| Settings: scopes, permissions, sandbox, env vars, tools | [settings.md](references/settings.md) |
| Status line: custom display, JSON input, scripts | [statusline.md](references/statusline.md) |
| Usage patterns: context management, verification, scaling | [best-practices.md](references/best-practices.md) |

**Read the relevant reference before making changes.**

## Concepts

<concepts>
**Skill** — Prompt template in `SKILL.md` that extends Claude's capabilities.
Loaded on-demand when description matches user request. Can include
`references/` for detailed content. Invoked with `/skill-name` or automatically.

**Plugin** — Distributable package containing skills, hooks, MCP servers,
output styles. Has `.claude-plugin/plugin.json` manifest. Installed from
marketplace or local path. Skills namespaced as `/plugin:skill`.

**Hook** — Deterministic automation triggered at lifecycle events (tool use,
session start, permission request). Three types: command (shell), prompt
(LLM decision), agent (multi-turn verification). Configured in settings or
plugin.

**MCP Server** — External tool/resource provider via Model Context Protocol.
Connects Claude to