Creates and modifies Claude Code sub-agents following best practices. Use when user requests creating, updating, modifying, improving, or editing sub-agents. Triggers include "create/make/new agent", "sub-agent for X", file paths with /agents/, "update/modify/improve agent Y". Handles agent structure, YAML frontmatter (name, description, tools, model), system prompt design, tool restrictions (minimal permissions), isolated context benefits. Delegates to edit-tool orchestrator if uncertain about tool type (agent vs skill vs command vs script).