ai-vision-mcp: Skill for Claude Code

.claude/skills/best-practices/SKILL.md

best-practices is a skill for Claude Code from tan-yong-sheng/ai-vision-mcp. It costs 49 tokens per session (2,945 once invoked), scanned A, a copy of best-practices, MIT.

A checklist for modern web development, covering website security, browser compatibility, and code quality.

In plain words
What is it for?
Use it for security audits, vulnerability checks, code-quality reviews, and modernising websites.
Why use it?
It helps find common security weaknesses, compatibility problems, and maintainability issues before they affect users or become harder to fix.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is tan-yong-sheng/ai-vision-mcp's own configuration. It tells Claude Code how to work on ai-vision-mcp itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything ai-vision-mcp configures →

Part of the ai-vision-mcp plugin — 29 skills, 1 plugin shipped together

Reuse

Borrowing it

Nothing to install: this file belongs to tan-yong-sheng/ai-vision-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/tan-yong-sheng/ai-vision-mcp/main/.claude/skills/best-practices/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/tan-yong-sheng/ai-vision-mcp

Made for: Claude Code.

Or install ai-vision-mcp, the plugin that ships this one along with the rest of its 29 skills, 1 plugin.

Wrote 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.

agentmods badge for best-practices

README.md
[![agentmods](https://agentmods.dev/badge/skills/tan-yong-sheng/ai-vision-mcp/best-practices/github.svg)](https://agentmods.dev/skills/tan-yong-sheng/ai-vision-mcp/best-practices)
Your own site
<a href="https://agentmods.dev/skills/tan-yong-sheng/ai-vision-mcp/best-practices"><img src="https://agentmods.dev/badge/skills/tan-yong-sheng/ai-vision-mcp/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.

agentmods 80×15 button for best-practices

Your own site · 80×15
<a href="https://agentmods.dev/skills/tan-yong-sheng/ai-vision-mcp/best-practices"><img src="https://agentmods.dev/badge/skills/tan-yong-sheng/ai-vision-mcp/best-practices.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,945 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00049 $0.02945
Opus 5 $0.00024 $0.01473
Sonnet 5 $0.00010 $0.00589
Haiku 4.5 $0.00005 $0.00295

Measured 12d ago against content hash f32182e2cd74, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

best-practices scanned grade A with 1 finding 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 12d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

const response = await fetch(url);
Origin

This is a copy

100% identical to best-practices — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/skills/best-practices/SKILL.md · 584 lines

How it starts

The opening of the file, as written. The whole thing — 584 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Best practices

Modern web development standards based on Lighthouse best practices audits. Covers security, browser compatibility, and code quality patterns.

Security

HTTPS everywhere

Enforce HTTPS:

<!-- ❌ Mixed content -->
<img src="http://example.com/image.jpg">
<script src="http://cdn.example.com/script.js"></script>

<!-- ✅ HTTPS only -->
<img src="https://example.com/image.jpg">
<script src="https://cdn.example.com/script.js"></script>

<!-- ✅ Protocol-relative (will use page's protocol) -->
<img src="//example.com/image.jpg">

HSTS Header:

Strict-Transport-Security: max-age=31536000; includeSubDomains; preload

Content Security Policy (CSP)

<!-- Basic CSP via meta tag -->
<meta http-equiv="Content-Security-Policy" 
      content="default-src 'self'; 
               script-src 'self' https://trusted-cdn.com; 
               style-src 'self' 'unsafe-inline';
               img-src 'self' data: https:;
               connect-src 'self' https://api.example.com;">

<!-- Better: HTTP header -->

CSP Header (recommended):

Content-Security-Policy: 
  default-src 'self';
  script-src 'self' 'nonce-abc123' https://trusted.com;
  style-src 'self' 'nonce-abc123';
  img-src 'self' data: https:;
  connect-src 'self' https://api.example.com;
  frame-ancestors 'self';
  base-uri 'self';
  form-action 'self';

Using nonces for inline scripts:

<script nonce="abc123">
  // This inline script is allowed
</script>

Security headers

# Prevent clickjacking
X-Frame-Options: DENY

# Prevent MIME type sniffing
X-Content-Type-Options: nosniff

# Enable XSS filter (legacy browsers)
X-XSS-Protection: 1; mode=block

# Control referrer information
Referrer-Policy: strict-origin-when-cross-origin

# Permissions policy (formerly Feature-Policy)
Permissions-Policy: geolocation=(), microphone=(), camera=()

No vulnerable libraries

# Check for vulnerabilities
npm audit
yarn audit

# Auto-fix when possible
npm audit fix

# Check specific package
npm ls lodash

Read the full file on GitHub · 584 lines

Changes

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.

  1. 12d ago First seen · 584 lines · 49 tokens per session scan A f32182e2cd74

Subscribe to this mod's changes

best-practices is a skill published in the GitHub repository tan-yong-sheng/ai-vision-mcp (78 stars, last pushed 5mo ago), licensed MIT. It adds 49 tokens to every session and 2,945 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). It is 100% identical to best-practices, differing in 0 lines, and is treated as a copy.