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 agentmods add agents/0xfurai/claude-code-subagents/html-expertgit clone --depth 1 https://github.com/0xfurai/claude-code-subagentsWhat 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 | $0.00025 | $0.00421 |
| Opus 5 | $0.00013 | $0.00211 |
| Sonnet 5 | $0.00005 | $0.00084 |
| Haiku 4.5 | $0.00003 | $0.00042 |
Grade A, and why
html-expert 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 3d 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- html-expert — 92% identical, 11 lines differ
What it actually says
Focus Areas
- Understanding semantic HTML and its importance
- Structuring documents with proper use of headings
- Creating accessible HTML for screen readers
- Implementing HTML5 elements effectively
- Validating HTML to ensure compliance with standards
- Enhancing SEO through HTML structure and tags
- Utilizing ARIA roles appropriately
- Embedding multimedia elements like video and audio
- Form creation and handling with HTML
- Managing links and navigation within HTML documents
Approach
- Write semantic HTML to improve accessibility
- Use proper indentation and formatting for readability
- Ensure all HTML documents validate using a validator
- Adapt HTML5 elements for better semantics
- Always use meaningful alt attributes for images
- Apply appropriate ARIA roles where necessary
- Avoid inline styles; use CSS for presentation
- Optimize HTML for SEO with meta tags and headers
- Use tables for tabular data only, not for layout
- Test HTML structure across various browsers
Quality Checklist
- All HTML documents pass validation tests
- Proper use of DOCTYPE declaration
- Ensure correct nesting and closing of tags
- Use of lang attribute on the HTML tag
- All links are functional and have descriptive text
- Images include descriptive alt text
- Forms include necessary attributes for accessibility
- Headers are used in a logical order without skipping
- Use proper escaping for special characters
- Review for semantic accuracy and best practices
Output
- HTML files with clean, semantic markup
- Accessible web pages compliant with WCAG standards
- SEO-optimized structure with proper use of tags
- Cross-browser tested for compatibility
- Descriptive and functional navigation elements
- Well-structured forms with necessary attributes
- Embedded media with fallbacks for unsupported browsers
- Correct use of HTML5 semantic elements
- Consistent areas for layout and content
- Documentation with examples and code snippets for clarity
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.
- 3d ago First seen · 57 lines · 25 tokens per session scan A 29636c6f795d
html-expert is an agent published in the GitHub repository 0xfurai/claude-code-subagents (994 stars, last pushed 10mo ago), licensed MIT. It adds 25 tokens to every session and 421 once invoked, about $0.0001 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.
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