This skill should be used when the user asks to "create an agent", "write a subagent", "generate agent definition", "add agent to plugin", "write agent frontmatter", "create autonomous agent", "build subagent", needs agent structure guidance, YAML frontmatter configuration, invocation criteria with examples, or wants to add specialized subagents to Claude Code plugins with proper capabilities lists and tool access definitions.
SkillScore91Maintained
Automatic
◆AI Engineer pack
Last verified 8/18/2026
What it changes
Passed 19 of 21 test cases with the skill, and 5 of 21 without it.
Without skill23%
With skill91%
Checks it passed that the model alone missed
Specifies model: sonnet in the frontmatter.
Sets the workspace folder path under PRDs/.
Assigns pink as the color for the UI/UX role.
and 17 more in the full report
15 fixed5 passed either way2 still failing0 broke
Pass-rate lift
+68 pp
Tokens
+182%
Agent turns
0%
Response time
-52%
Model gemini-3.6-flashMeasured 8/18/2026v620 of 22 cases passed with skill · 21 comparable
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 15 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 15
Prompt
If an agent is named `cache-optimizer`, what exact directory name should be used for its accompanying technical skill inside `.claude/skills/`?
What was checked, without and with the skill
Checked
Without skill
With skill
Appends the -skill suffix resulting in cache-optimizer-skill.
Missed
Passed
case-20 · gemini-3.6-flash · 8/18/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md553 linessingle file
Agent Creator Skill
Purpose: Guide creation of Claude Code agents following Anthropic official best practices.
When to use: Creating new agents, refactoring existing agents, validating agent structure.
🎯 Core Principles
Agent Structure Philosophy
Minimal agents (~150 lines): Only identity, role, boundaries, and skill invocation
Comprehensive skills: All technical procedures, workflows, and references
This skill should be used when the user asks to "create an agent", "add an agent", "write a subagent", "agent frontmatter", "when to use description", "agent examples", "agent tools", "agent colors", "autonomous agent", or needs guidance on agent structure, system prompts, triggering conditions, or agent development best practices for Claude Code plugins.