Addy OsmaniAgent Skills

Agent Skills by Addy Osmani is an open-source collection of 20 production-grade engineering skills designed to guide AI coding agents through every phase of software development. Skills encode the workflows, quality gates, and best practices that senior engineers apply — from idea refinement and spec writing through to shipping and monitoring. Rather than generic prompts, each skill is a structured, step-by-step workflow with verification gates and anti-rationalization tables that prevent agents from skipping critical steps.

• 20 Core Skills covering the full development lifecycle: Define, Plan, Build, Verify, Review, and Ship phases — each packaged as a SKILL.md with steps, checkpoints, and exit criteria.
• 7 Slash Commands (/spec, /plan, /build, /test, /review, /code-simplify, /ship) that map directly to the development lifecycle and activate the right skills automatically.
• Multi-agent support — works with Claude Code (via marketplace install), Cursor, Gemini CLI, Windsurf, OpenCode, GitHub Copilot, Kiro IDE, and any agent that accepts Markdown system prompts.
• Agent Personas — three pre-configured specialist personas (code-reviewer, test-engineer, security-auditor) for targeted, role-specific reviews.
• Reference Checklists for testing patterns, security (OWASP Top 10), performance (Core Web Vitals), and accessibility (WCAG 2.1 AA).
• Anti-rationalization tables in every skill document common excuses agents use to skip steps (e.g., "I'll add tests later") with documented counter-arguments.
• Verification-first design — every skill ends with evidence requirements (tests passing, build output, runtime data) so "seems right" is never sufficient.
• Google engineering practices baked in — Hyrum's Law, Beyonce Rule, test pyramid, trunk-based development, Shift Left, Chesterton's Fence, and more are embedded directly into workflows.
• Progressive disclosure — SKILL.md is the entry point; supporting references load only when needed to keep token usage minimal.
• MIT License — free to use, modify, and distribute in personal projects, teams, and commercial tools.