Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add HoangNguyen0403/agent-skills-standard --skill common-best-practicesgit clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standardWrote 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/skills/hoangnguyen0403/agent-skills-standard/common-best-practices)<a href="https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/common-best-practices"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/common-best-practices/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/skills/hoangnguyen0403/agent-skills-standard/common-best-practices"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/common-best-practices.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00052 | $0.00425 |
| Opus 5 | $0.00026 | $0.00212 |
| Sonnet 5 | $0.00010 | $0.00085 |
| Haiku 4.5 | $0.00005 | $0.00042 |
Grade A, and why
common-best-practices 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 13d 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.
What it actually says
Global Best Practices
Priority: P0 (CRITICAL)
Core Principles
- SOLID: Follow SRP (One reason to change), OCP (Open to extension), LSP, ISP, DIP.
- KISS/DRY/YAGNI: Favor readability. Abstract repeated logic. No " in case" code.
- Naming: Use intention-revealing names (
isUserAuthenticated>checkUser). Match language casing.
Code Hygiene
- Size Limits: Functions < 30 lines. Services < 600 lines. Utils < 400 lines.
- Early Returns: Use guard clauses. Avoid deep nesting.
- Comments: Explain why, not what. Refactor bad code; don't comment it.
- Input: Validate/sanitize all external inputs.
Anti-Patterns
- No Hardcoded Constants: Use named config/env vars.
- No Deep Nesting: Use guard clauses.
- No Global State: Prefer dependency injection.
- No Empty Catches: Always handle, log, or rethrow.
References
- Code Structure Patterns — file/function organization
- Effectiveness Guide — practical application examples
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 13d ago First seen · 52 lines · 52 tokens per session scan A e714c24b066e
common-best-practices is a skill published in the GitHub repository HoangNguyen0403/agent-skills-standard (565 stars, last pushed 3d ago), licensed MIT. It adds 52 tokens to every session and 425 once invoked, about $0.0003 per session on Opus 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 skills, from other repositories
code-quality
Comprehensive frontend code review for TypeScript 6 and React 19.2 — clean code principles, component patterns, type safety, accessibility, and performance. Use when user says "review code", "refactor", "check this PR", or before merging changes.
spotpatch
A development workflow for React that connects a selected page element to its JSX or TSX source code and gathers context for review.
ralph
Ralph - persistent self-referential execution loop wrapping ultrawork with independent verifier verification.
review
Full QA review pipeline covering security audit (OWASP Top 10), performance analysis, accessibility check (WCAG 2.1 AA), and code quality review.
design-lenses
Critique a game's design through Schell's lenses, MDA and systems thinking, ranking findings by severity with fixes. Design-level review, not bugs or feel tuning.
Component Test Scaffold (Next.js)
Generate React/Next.js component test skeletons (RTL) from specifications.