agent-builder
Use when creating, improving, or troubleshooting Claude Code subagents. Expert guidance on agent design, system prompts, tool access, model selection, and best practices for building specialized AI assistants.
npx skills add majiayu000/claude-skill-registry --skill agent-builder-majiayu000-claude-skill-registr-86e748e2 --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
What it does
Guides the user through creating, improving, or troubleshooting Claude Code subagents. Provides expert guidance on agent design, system prompt engineering, tool configuration, and delegation patterns.
How it works
- Triggered when the user asks to create a new subagent, improve an existing agent, configure tools, diagnose invocation issues, understand agent-vs-skill-use, or discuss delegation.
- Presents a step-by-step process: identify use case, design scope with best practices, write a system prompt with structure, configure tool access and model, and outline maintenance considerations.
- Includes patterned examples for typical subagents (code-reviewer, debugger, data-scientist, test-generator) and outlines tool/model configurations and output expectations.
- Describes available tools (Read, Write, Edit, Bash, Grep, Glob, WebFetch, WebSearch) and model options (sonnet, opus, haiku, inherit).
When to use it
- Use when creating a new subagent
- Use when improving an existing agent
- Use when configuring tool access or troubleshooting agent invocation
- Use when understanding when to use agents vs skills vs commands
- Use when planning agent chaining or delegation patterns
What it can touch
- Tool configuration patterns at high level, including which tools to grant or restrict (Read, Write, Edit, Bash, Grep, Glob, WebFetch, WebSearch, and MCP tools), and model selection.
- Frontmatter-like blocks describing agent name, description, tools, and model, and typical system prompts.
Caveats
- Describes best practices and patterns but does not guarantee outcomes for subagent performance.
- Content must be implemented by the user; it is guidance on design and configuration, not a runtime guarantee.
# Agent Builder - Claude Code Subagent Expert Use this skill when creating, improving, or troubleshooting Claude Code subagents. Provides expert guidance on agent design, system prompt engineering, tool configuration, and delegation patterns. ## When to Use This Skill Activate this skill when: - User asks to create a new subagent - User wants to improve an existing agent - User needs help with agent configuration or tool access - User is troubleshooting agent invocation issues - User wants to understand when to use agents vs skills vs commands - User asks about agent chaining or delegation patterns ## Quick Reference ### Agent File Structure ```markdown --- name: agent-name description: When and why to use this agent tools: Read, Write, Bash(git *) model: sonnet --- Your detailed system prompt defining: - Agent role and expertise - Problem-solving approach - Output format expectations - Specific constraints or requirements ``` ### File Locations **Project agents** (shared with team, highest priority): ``` .claude/agents/my-agent.md ``` **Personal agents** (individual use, lower priority): ``` ~/.claude/agents/my-agent.md ``` **Plugin agents** (from installed plugins): ``` <plugin-d
- When to Use This Skill
- Quick Reference
- Agent File Structure
- File Locations
- Creating Effective Subagents
- Step 1: Identify the Use Case
- Step 2: Design Agent Scope
- Step 3: Write the System Prompt
- Step 4: Configure Tools Access
- Step 5: Choose Model
- Step 6: Write Clear Description
- Agent Patterns
- Pattern 1: Code Reviewer
- Pattern 2: Debugger
What does the agent-builder skill do?
Use when creating, improving, or troubleshooting Claude Code subagents. Expert guidance on agent design, system prompts, tool access, model selection, and best practices for building specialized AI assistants.
How do I install it?
Run `npx skills add majiayu000/claude-skill-registry --skill agent-builder-majiayu000-claude-skill-registr-86e748e2 --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From majiayu000/claude-skill-registry, a repository with 534 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.