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 EnkrateiaLucca/skills --skill html-tool-generatorgit clone --depth 1 https://github.com/EnkrateiaLucca/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/skills/enkrateialucca/skills/html-tool-generator)<a href="https://agentmods.dev/skills/enkrateialucca/skills/html-tool-generator"><img src="https://agentmods.dev/badge/skills/enkrateialucca/skills/html-tool-generator/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/enkrateialucca/skills/html-tool-generator"><img src="https://agentmods.dev/badge/skills/enkrateialucca/skills/html-tool-generator.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 | $0.00035 | $0.03896 |
| Opus 5 | $0.00017 | $0.01948 |
| Sonnet 5 | $0.00007 | $0.00779 |
| Haiku 4.5 | $0.00003 | $0.00390 |
Grade B, and why
html-tool-generator scanned grade B with 2 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 9d 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.
Sends data to an external URLmediumData exfiltration
A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.
const response = await fetch('https://api.anthropic.com/v1/messages', { method: 'POST', 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, options); How it starts
The opening of the file, as written. The whole thing — 649 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Single-File HTML Tool Generator
Generate self-contained HTML tools that work entirely in the browser. Based on Simon Willison's patterns for building useful utilities without servers, build steps, or frameworks.
When to Use This Skill
Use this skill when the user requests:
- Building a single-file HTML utility or tool
- Creating a browser-based tool that uses an API
- Making a client-side data processor or converter
- Building a tool that should work offline or without a server
- Creating utilities for LLM API testing/interaction
Trigger phrases: "create an HTML tool", "build a single-file tool", "make a browser utility", "create a client-side tool", "build an API playground"
Core Principles
1. Single File, No Build Steps
- Everything in one HTML file: HTML, CSS, and JavaScript
- Never use React, Vue, or anything requiring compilation
- No JSX, no TypeScript, no bundlers
- Vanilla JavaScript only
2. CDN Dependencies Only
- Load libraries from cdnjs, jsDelivr, or unpkg
- Always use versioned URLs for stability
- Common libraries:
markedfor Markdown renderinghighlight.jsfor syntax highlightingpdf.jsfor PDF handlingTesseract.jsfor OCRPyodidefor Python execution
3. API Keys in localStorage (NEVER in HTML)
- Prompt user for API keys on first use
- Store in localStorage immediately
- Never send keys to any server
- Provide a way to clear/reset stored keys
4. State Management
- URL hash/params for shareable state (configs, settings)
- localStorage for user data (drafts, preferences)
- No server-side storage needed
Template Structure
Every HTML tool follows this anatomy:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Tool Name</title>
<style>
/* All CSS inline - no external stylesheets */
</style>
</head>
<body>
<!-- Tool UI -->
<script>
/* All JavaScript inline - no external scripts except CDN libs */
</script>
</body>
</html>
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.
- 9d ago First seen · 649 lines · 35 tokens per session scan B b3f4a45b608d
html-tool-generator is a skill published in the GitHub repository EnkrateiaLucca/skills (3 stars, last pushed 3mo ago), licensed MIT. It adds 35 tokens to every session and 3,896 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 2 findings (sends data to an external url, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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