Claude Code Automation Map of automation surfaces in Claude Code and which one to reach for. Internal-only — relies on what the user already has installed. Decision matrix — which surface to use | Need | Surface | Lives in | |---|---|---| | Run shell command on every tool event | Hook | | | Encapsulate domain knowledge + workflow | Skill | | | Deterministic multi-step flow the user invokes | Slash command | | | Isolated worker spawned from main agent | Sub-agent | | | Coordinated multi-agent pattern | Agent team | | | External tool surface (APIs, CLIs) | MCP server | or | | Package the above…