- Hooks — 25 lifecycle points (
UserPromptSubmit,PreToolUse, …). Deterministic guards, not model-mediated. - Subagents — isolated context windows for bounded tasks. Only the summary returns to main.
- Skills — optional capability bundles Claude can auto-load; frontmatter declares when to use.
Anthropic · Skills docs
Default extensibility recipe with Claude Code clients: skills for repeatable workflows, subagents for bounded heavy lifting, hooks for safety/budget enforcement.