Claude Code CLI is Anthropic's flagship terminal agent. While extraordinary at ad-hoc shell tasks, its true power unlocks when configured with domain-specific skills—declarative Markdown instructions that transform Claude into an autonomous Staff Engineer.

1. Anatomy of a Claude Code Skill (SKILL.md)

Skills live inside .claude/skills/<skill-name>/SKILL.md. They define precise triggers and repeatable operational workflows with zero hallucination risk.

.claude/skills/claude-pr-reviewer/SKILL.md

# Skill: Autonomous Pull Request Reviewer

## Trigger
Use when reviewing a GitHub Pull Request or validating branch diffs.

## Execution Workflow
1. Run `git diff origin/main...HEAD`
2. Audit for hardcoded secrets, SQL injection risks, and missing tests.
3. Output structured findings categorized by Severity (Blocker / Nitpick).

2. Enforcing Deterministic Quality Gates

Pairing skills with pre-commit hooks or CI triggers guarantees that no code is merged without passing security audits, test coverage thresholds, and architectural boundary checks.

Anthropic Claude Code CLI: Building Autonomous Custom Skills for Codebase Automation

1. Anatomy of a Claude Code Skill (SKILL.md)

2. Enforcing Deterministic Quality Gates

Claude Code Custom Skills Pack: 10 Turnkey Autonomous Software Engineering Skills