Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add f-labs-io/agent-html-skills/plugin install html-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/f-labs-io/agent-html-skills/html-spec-planning)<a href="https://agentmods.dev/skills/f-labs-io/agent-html-skills/html-spec-planning"><img src="https://agentmods.dev/badge/skills/f-labs-io/agent-html-skills/html-spec-planning/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/f-labs-io/agent-html-skills/html-spec-planning"><img src="https://agentmods.dev/badge/skills/f-labs-io/agent-html-skills/html-spec-planning.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 | $0.00096 | $0.01890 |
| Opus 5.5 | $0.00038 | $0.00756 |
| Sonnet 5.5 | $0.00019 | $0.00378 |
| Haiku 4.5 | $0.00010 | $0.00189 |
Grade A, and why
html-spec-planning 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 — 99 lines — stays where its author put it; the contents beside it link to each section on GitHub.
HTML Spec, Planning & Exploration
Use HTML as the working surface for thinking through problems — brainstorms, alternative explorations, mockups, and implementation plans. Markdown specs over ~100 lines stop getting read; HTML specs get read because they're navigable, visual, and shareable as a link.
Pre-flight — run BEFORE writing the artifact
Invoke html-skills:html-skills-listen (Skill tool) first; it is idempotent. If it returns a URL, inject it verbatim as window.__CLAUDE_SUBMIT_URL__ in the HTML you are about to write, ?t= query string included (a local, single-session loopback handshake — not a credential). If it reported web/sandbox mode, leave that line out; submitToClaude then falls back to clipboard mode.
When to use this skill
- "Write a spec / RFC / design doc / proposal for X"
- "I'm not sure how to approach X — explore the options"
- "Make me an implementation plan for X"
- "Lay out the tradeoffs for X"
- Whenever the planning artifact will be reviewed by humans, or later read by another Claude session for implementation
For tree-shaped idea capture the user edits, use html-mind-map; for N rendered alternatives to compare, use html-brainstorm-grid.
Output requirements
Save with a descriptive filename like <topic>-spec.html or <topic>-plan.html so multiple planning artifacts on one project compose into a readable folder rather than colliding on output.html.
Core structure
A planning artifact has predictable sections. Use them or a deliberate variation:
- Title + one-sentence framing — what this document is and isn't
- Context / problem — what we're trying to solve, who cares
- Constraints — non-negotiables, scope boundaries
- Approach(es) — either one chosen direction or a comparison of N
- Mockups / diagrams — visuals for any spatial or relational concept
- Data flow / sequence — if relevant, an SVG or HTML+CSS diagram
- Implementation plan — concrete steps, files to touch, code snippets
- Open questions — things the writer doesn't know yet, surfaced not buried
- Out of scope — explicit "we are not solving X here" list
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 Changed · +1 lines 4e396f79d473
- 2mo ago Changed · +13 lines · +1 tokens per session 7867901c2a8b
- 2mo ago First seen · 85 lines · 95 tokens per session scan A 2b5ec686a40e
html-spec-planning is a skill published in the GitHub repository f-labs-io/agent-html-skills (68 stars, last pushed 1mo ago), licensed MIT. It adds 96 tokens to every session and 1,890 once invoked, about $0.0004 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.
html-spec-planning compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| html-spec-planningf-labs-io/agent-html-skills | Skill | 68 | 1mo ago | MIT | A | 96 | Claude Code |
| imagegenopenai/codex | Skill | 133k | yesterday | Apache-2.0 | A | 113 | Codex |
| playwright-climicrosoft/playwright | Skill | 99k | yesterday | Apache-2.0 | A | 19 | Claude Code |
| local-ai-agentsmicrosoft/ai-agents-for-beginners | Skill | 79k | 4d ago | MIT | A | 200 | Claude Code, Codex |
| systematic-debuggingobra/superpowers | Skill | 313k | 3d ago | MIT | A | 21 | Claude Code |
| next-cache-components-adoptionvercel/next.js | Skill | 143k | yesterday | MIT | A | 95 | Claude Code |
| next-partial-prefetching-adoptionvercel/next.js | Skill | 143k | yesterday | MIT | A | 103 | Claude Code |