Addy Osmani's agent skills for Claude Code
agent-skills is Addy Osmani's pack of 25 engineering skills for coding agents, organized as a development lifecycle: define, plan, build, verify, review and ship, with a slash command for each stage.
/plugin install agent-skills@addy-agent-skillsAddy Osmani's pack writes down the workflows and quality gates a senior engineer follows, so an agent applies them the same way every time. It holds 25 skills, 24 for stages of the lifecycle plus one that maps a request to the right skill, and each comes with steps, checks and a table of excuses the agent should not accept from itself. The license is MIT. For the basics, see Claude Code skills.
The nine commands
| Command | Stage | Principle, per the README |
|---|---|---|
/spec | Define what to build | Spec before code |
/plan | Plan how | Small, atomic tasks |
/build | Build in slices | One slice at a time |
/test | Prove it works | Tests are proof |
/constraints | Set the quality bar | Decide it once, enforce it everywhere |
/review | Review before merge | Improve code health |
/webperf | Audit web performance | Measure before you optimize |
/code-simplify | Simplify | Clarity over cleverness |
/ship | Release | Faster is safer |
/build auto writes the plan from an approved spec and implements every task in one pass after you approve the plan once. Skills also trigger on their own: designing an API brings in the API design skill, building UI the front-end one.
Skills worth knowing
- interview-me: asks one question at a time until it is about 95% sure what you want.
- spec-driven-development: a short requirements document before any code.
- incremental-implementation: thin vertical slices, each tested and committed.
- source-driven-development: grounds framework decisions in official documentation and flags what it could not verify.
- doubt-driven-development: a fresh-context, adversarial review of each important decision while the work runs.
- code-review-and-quality: reviews on five axes, with changes kept to about 100 lines.
- security-and-hardening, performance-optimization, ci-cd-and-automation and deprecation-and-migration for the later stages.
How to install it
Claude Code, from the author's marketplace:
/plugin marketplace add addyosmani/agent-skills
/plugin install agent-skills@addy-agent-skillsIf the install fails with an SSH permission error, add the marketplace by its full HTTPS address, https://github.com/addyosmani/agent-skills.git. For any of 70-plus agents, or to pick single skills:
npx skills add addyosmani/agent-skills
npx skills add addyosmani/agent-skills --skill interview-meA single-skill install copies only that skill's folder, so links to the shared checklists in the repo's references/ folder will not resolve. Install the whole pack if you want them.
When to use it
- Teams that want one shared definition of "done" for agent-written code.
- New projects, where the full lifecycle from
/specto/shipfits. On an existing codebase the author's adoption guide suggests starting with the verification skills.
Superpowers covers similar ground with a stricter fixed order. Pick one; two process packs at once will compete for the same steps. If you only want the questioning step, grill-me is one skill instead of a pack.
Sources
- addyosmani/agent-skills README — GitHub, accessed October 2026