Imported from borghei/claude-skills (engineering/claude-code-mastery/SKILL.md). Install upstream with npx skills add borghei/claude-skills --skill claude-code-mastery. Copyright stays with the author (MIT).

Claude Code Mastery

Expert skill for Claude Code CLI -- CLAUDE.md optimization, skill authoring, subagent creation, hooks automation, and context engineering.

Keywords: claude-code, claude-cli, CLAUDE.md, skill-authoring, subagents, hooks, context-window, token-budget, MCP-servers, worktrees, permission-modes, prompt-engineering, context-engineering, slash-commands

Core Capabilities

• CLAUDE.md optimization — audit, restructure, compress, and hierarchize config files for token efficiency.
• Skill authoring — scaffold and write discoverable skill packages with correct layout and frontmatter.
• Subagent creation — define scoped agents with allowed-tools and structured custom instructions.
• Hooks automation — wire PreToolUse/PostToolUse/Stop lifecycle scripts via .claude/settings.json.
• Context engineering — measure and manage the context-window token budget across a codebase.

When to Use

• Authoring, structuring, or optimizing a CLAUDE.md file for any project.
• Scaffolding a new skill package or creating a Claude Code subagent.
• Configuring hooks for automated quality, security, or workflow steps.
• Auditing and reducing context-window consumption.

Clarify First

Before scaffolding or optimizing, confirm these inputs. If any is unknown or vague, ASK — do not assume:

• Which task — scaffold a new skill, optimize a CLAUDE.md, create a subagent, or analyze context budget (selects skill_scaffolder.py vs claudemd_optimizer.py vs context_analyzer.py)
• Target identity — for a new skill: its name, domain, and one-line description; for optimization: the file or project path (the inputs the scripts require)
• Token budget — the target ceiling (sets --token-limit and what counts as over-budget)

Stop rule: ask only the 2-3 that most change the output. If the user says "just draft it," proceed and list your assumptions at the top of the artifact.

Quick Start

# Scaffold a new skill package
python scripts/skill_scaffolder.py my-new-skill --domain engineering --description "Brief description"

# Analyze and optimize an existing CLAUDE.md
python scripts/claudemd_optimizer.py path/to/CLAUDE.md

# Estimate context window usage across a project
python scripts/context_analyzer.py /path/to/project

# All tools support JSON output
python scripts/claudemd_optimizer.py CLAUDE.md --json

Tools

All tools support --json. See references/tool-reference.md for full parameter tables and output formats.

References

Load the reference that matches the task — keep this file lean and pull detail on demand:

• references/workflows.md — the five numbered playbooks: optimize a CLAUDE.md, author a skill, create a subagent, configure hooks, and manage the context budget. Read when executing any of those tasks step-by-step.
• references/quick-reference.md — slash commands, permission modes, CLAUDE.md loading order, MCP servers, the troubleshooting table, and success criteria. Read for at-a-glance lookups or when debugging configuration.
• references/tool-reference.md — full parameter tables and output formats for the three Python tools. Read when scripting the tools or interpreting their JSON output.
• references/skill-authoring-guide.md — comprehensive reference for writing effective skills, from YAML frontmatter to structure. Read when authoring a skill in depth.
• references/subagent-patterns.md — guide to creating and using subagents for parallel work and scoped tasks. Read when designing a subagent.
• references/hooks-cookbook.md — practical hook recipes for code quality, security enforcement, and workflow automation. Read when building hooks.

Templates: assets/skill-template.md, assets/agent-template.md

Scope & Limitations

This skill covers:

• Authoring, structuring, and optimizing CLAUDE.md files for any project
• Scaffolding new skill packages with correct directory layout and frontmatter
• Creating and configuring Claude Code subagents with scoped tool access
• Analyzing and managing context window token budgets across a codebase

This skill does NOT cover:

• Writing application source code or implementing business logic (see senior-fullstack, senior-backend)
• MCP server development or custom transport protocols (see mcp-server-builder)
• Advanced prompt engineering techniques for LLM applications (see senior-prompt-engineer)
• CI/CD pipeline configuration or deployment automation (see senior-devops, ci-cd-pipeline-builder)

Integration Points