Build Custom Claude Code Sub-Agents

Build reusable agents with focused expertise, scoped tool access, and project or user scope.

Steps

1. Define agent purpose, trigger conditions, and required tools (single responsibility)
2. Create .md file in .claude/agents/ (project) or ~/.claude/agents/ (user)
3. Write frontmatter: name, description, tools, model fields
4. Write focused system prompt with specific instructions and constraints
5. Test automatic and explicit invocation; commit project agents to version control

For detailed instructions, see instructions.md.