addyosmani/agent-skills is a collection of reusable workflows, quality checks, commands, and other instructions that guide AI coding agents through software development. It is for developers who want agents to follow consistent engineering practices, and the catalogue entries are its packaged skills, commands, agents, plugins, instructions, and hooks.
Borrowing it
Nothing to install: this file belongs to addyosmani/agent-skills. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/addyosmani/agent-skills/main/CLAUDE.mdgit clone --depth 1 https://github.com/addyosmani/agent-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/addyosmani/agent-skills/claude-md)<a href="https://agentmods.dev/instructions/addyosmani/agent-skills/claude-md"><img src="https://agentmods.dev/badge/instructions/addyosmani/agent-skills/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/addyosmani/agent-skills/claude-md"><img src="https://agentmods.dev/badge/instructions/addyosmani/agent-skills/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00909 | $0.00909 |
| Opus 5.5 | $0.00364 | $0.00364 |
| Sonnet 5.5 | $0.00182 | $0.00182 |
| Haiku 4.5 | $0.00091 | $0.00091 |
Grade A, and why
agent-skills CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 61 lines — stays where its author put it; the contents beside it link to each section on GitHub.
agent-skills
This is the agent-skills project — a collection of production-grade engineering skills for AI coding agents.
Scope: This file configures agents working on the
addyosmani/agent-skillsrepository itself, not other projects. Don't copy it into another project or a global agent configuration; the reusable assets are the skills inskills/.
Project Structure
skills/ → Core skills (SKILL.md per directory)
agents/ → Reusable agent personas (code-reviewer, test-engineer, security-auditor, web-performance-auditor)
hooks/ → Session lifecycle hooks
.claude/commands/ → Slash commands (/spec, /plan, /build, /test, /review, /code-simplify, /ship; plus /webperf specialist audit)
references/ → Supplementary checklists (testing, performance, security, accessibility, observability)
evals/ → Skill eval cases + framework (see evals/README.md)
docs/ → Setup guides for different tools
Skills by Phase
Define: interview-me, idea-refine, spec-driven-development Plan: planning-and-task-breakdown Build: incremental-implementation, test-driven-development, context-engineering, source-driven-development, doubt-driven-development, frontend-ui-engineering, api-and-interface-design Verify: browser-testing-with-devtools, debugging-and-error-recovery Review: code-review-and-quality, code-simplification, security-and-hardening, performance-optimization Ship: git-workflow-and-versioning, ci-cd-and-automation, deprecation-and-migration, documentation-and-adrs, observability-and-instrumentation, shipping-and-launch
Conventions
- Every skill lives in
skills/<name>/SKILL.md - YAML frontmatter with
nameanddescriptionfields - Description starts with what the skill does (third person), followed by trigger conditions ("Use when...")
- Every skill has: Overview, When to Use, Process, Common Rationalizations, Red Flags, Verification
- Shared references are in the root
references/directory; the emerging convention for self-contained, distributable skills keeps a skill's own references insideskills/<name>/references/ - Supporting files only created when content exceeds 100 lines
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 61 lines · 909 tokens per session scan A f03b7aaf2c08
agent-skills CLAUDE.md is an instructions file published in the GitHub repository addyosmani/agent-skills (108,203 stars, last pushed 5d ago), licensed MIT. It adds 909 tokens to every session, about $0.0036 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.