meta-agent-creator

Custom Agent Creator

Overview

Subagents are specialized AI assistants defined as Markdown files with YAML frontmatter. Each subagent runs in its own context window with a custom system prompt, specific tool access, and independent permissions. When a task matches a subagent's description, the parent conversation delegates to it automatically, preserving main context while enforcing constraints.

When to use: Isolating high-volume operations (tests, logs), enforcing read-only access for reviewers, routing simple tasks to cheaper models, running parallel research, creating reusable team workflows.

When NOT to use: Tasks requiring frequent back-and-forth, quick targeted changes, workflows needing nested delegation (subagents cannot spawn subagents), latency-sensitive operations where fresh context gathering is costly.

Quick Reference

Pattern	Configuration	Key Points
File location (project)	.claude/agents/name.md	Shared via version control, priority 2
File location (user)	~/.claude/agents/name.md	Available across all projects, priority 3
Required fields	name, description	Only two fields are mandatory
Tool restriction	tools: Read, Grep, Glob	Allowlist; inherits all if omitted
Tool denial	disallowedTools: Write, Edit	Denylist; removed from inherited set
Model selection	model: haiku	Options: sonnet, opus, haiku, inherit (default)
Permission mode	permissionMode: dontAsk	Controls permission prompt behavior
Skill preloading	skills: [auth, api-patterns]	Injected at startup; no inheritance from parent
Lifecycle hooks	hooks: { PreToolUse: [...] }	Validate or block tool usage conditionally
CLI-defined agent	claude --agents '{...}'	Session-only, highest priority, JSON format
Interactive creation	/agents command	Guided setup with Claude generation
Proactive triggers	"Use proactively after..."	Include in description for auto-delegation

Common Mistakes

Mistake	Correct Pattern
Using opus for simple checklist reviews	Use haiku for read-only reviews and style checks
Omitting output format in system prompt	Include structured output template for consistent results
Listing tools explicitly when all are needed	Omit tools field to inherit all tools including MCP
Expecting skills from parent conversation	Explicitly list skills in the skills field
Generic description without triggers	Include specific trigger phrases like "Use proactively when..."
Giving a single agent too many responsibilities	Design focused agents with one clear purpose each
Using bypassPermissions without caution	Prefer acceptEdits or dontAsk for safer automation
Creating deeply nested agent workflows	Chain subagents from main conversation; nesting is not supported

Delegation

• Agent pattern discovery: Use Explore agent to find existing agents in .claude/agents/
• Interactive creation: Use /agents command for guided setup with Claude generation
• Code review of agent files: Use Task agent to validate system prompts and configuration

References

• Agent configuration: YAML fields, file locations, and priority order
• Tool selection: access patterns, common combinations, and model guide
• Templates: ready-to-use agent patterns for common workflows