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-throwaway-editor)<a href="https://agentmods.dev/skills/f-labs-io/agent-html-skills/html-throwaway-editor"><img src="https://agentmods.dev/badge/skills/f-labs-io/agent-html-skills/html-throwaway-editor/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-throwaway-editor"><img src="https://agentmods.dev/badge/skills/f-labs-io/agent-html-skills/html-throwaway-editor.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 | $0.00147 | $0.03497 |
| Opus 5 | $0.00073 | $0.01749 |
| Sonnet 5 | $0.00029 | $0.00699 |
| Haiku 4.5 | $0.00015 | $0.00350 |
Grade A, and why
html-throwaway-editor 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 5d 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 — 173 lines — stays where its author put it; the contents beside it link to each section on GitHub.
HTML Throwaway Editor
When describing what you want to do is harder than just doing it, build a one-off editor. Not a product. Not a reusable tool. A single HTML file purpose-built for this one piece of data, with one Submit button at the end that sends the result back to the agent.
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
- "I need to reprioritize / reorder / triage these N things"
- "Help me edit / curate / annotate / tag this dataset"
- "I want to tune / pick / configure these values" (where the values aren't simple text)
- "Build me a quick editor for X"
- Any time the user describes a manipulation that would be painful to do in chat but easy with a UI
Output requirements
Pre-populate with the actual data the user provided (after the secrets pass below) — never make them paste it again. End with one Submit button that sends the edited structure back in the standard envelope.
The Submit button is non-negotiable. An editor without it is a dead-end; "throwaway" means the result lives outside the artifact, not inside it.
Secrets are never embedded
Before pre-populating, scan the input for secret-shaped values. Mask anything that matches:
- Key names matching
/(key|secret|token|passw|credential|private|auth|dsn|connection[_-]?string)/i. - Known prefixes:
AKIA,ghp_/gho_,sk-,xox,AIza,eyJ-prefixed JWTs, PEMPRIVATE KEYblocks. - URLs with userinfo —
scheme://user:pass@hostconnection strings. - Secret-bearing sources: if the source file is secret-bearing by convention (
.env,*credentials*,*secret*,.npmrc, key/PEM files), treat every value in it as secret by default — don't rely on the regexes alone. - High-entropy strings ≥ 20 chars — in config/env-shaped inputs (Pattern B) only; treat a bare entropy hit as "mask unless the user confirms it's not a secret". Don't apply this heuristic to dataset or annotation rows (Patterns D/E), where hashes, UUIDs, and base64 are legitimate payload.
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.
- 5d ago Changed · -61 lines ad3a779571fb
- 9d ago First seen · 234 lines · 147 tokens per session scan A 679b96c6ffdd
html-throwaway-editor is a skill published in the GitHub repository f-labs-io/agent-html-skills (55 stars, last pushed 6d ago), licensed MIT. It adds 147 tokens to every session and 3,497 once invoked, about $0.0007 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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