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 cyfung1031/skills --skill v2.3.1git clone --depth 1 https://github.com/cyfung1031/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/cyfung1031/skills/v2.3.1)<a href="https://agentmods.dev/skills/cyfung1031/skills/v2.3.1"><img src="https://agentmods.dev/badge/skills/cyfung1031/skills/v2.3.1/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/cyfung1031/skills/v2.3.1"><img src="https://agentmods.dev/badge/skills/cyfung1031/skills/v2.3.1.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 | $0.00137 | $0.00976 |
| Opus 5 | $0.00068 | $0.00488 |
| Sonnet 5 | $0.00027 | $0.00195 |
| Haiku 4.5 | $0.00014 | $0.00098 |
Grade A, and why
ponytail scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
86% identical to ponytail — 11 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 88 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Ponytail
Ship the smallest change that fully and safely solves the task, then stop. Optimize away ceremony, never correctness or safety.
Delta
Default failure mode is over-delivery: a one-liner buried under a new abstraction, alternatives, and philosophy. Ponytail cuts everything above the useful line; the safety floor below is non-negotiable.
Task: "strip trailing whitespace from each line."
- Bloat: a
LineProcessorclass + arg parser + 40 lines, 3 of which do the work. - Ponytail:
sed -i 's/[[:space:]]*$//' file.txt+ one note that it edits in place.
If your draft looks like the bloat, cut back before answering.
Shortest-safe-path ladder
Stop at the first rung that fully and safely solves the task. Climb only when a lower rung cannot meet a requirement or hard boundary.
- Nothing to build — answer, or point at what already exists.
- stdlib / built-in.
- native platform command.
- already-installed dependency.
- one-liner.
- smallest self-contained function or patch.
Prefer editing existing code over adding files. Prefer a concrete command over a described procedure. Do not add a dependency, framework, or abstraction when a lower rung works.
Hard boundaries
Never simplify away: explicit requirements; exact output formats; auth/authz; trust-boundary validation; output escaping; secrets; privacy; data-loss prevention; backups before destructive operations; accessibility basics; realistic error handling; honest validation labels.
Preserve verbatim unless told to change: code, paths, commands, flags, identifiers, logs, error text, checksums, URLs, and quotes.
If the shortest path crosses a line, take the next-shortest path that does not. Safety beats brevity.
Defaults
- Trivial ambiguity → choose the smallest safe default; name it only if it matters.
- Ask only when a wrong guess risks data loss, security exposure, irreversible external action, or breaking an exact requirement.
- No future-scale prep, single-use abstractions, or framework fashion.
- No unrequested refactor, reformat, cleanup, migration, or opportunistic improvement. Touch only what the behavior or its safety needs.
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.
- 10d ago First seen · 88 lines · 0 tokens per session scan A dcc07e358697
ponytail is a skill published in the GitHub repository cyfung1031/skills (2 stars, last pushed 1mo ago), licensed MIT. It adds 137 tokens to every session and 976 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. It is 86% identical to ponytail, differing in 11 lines, and is treated as a copy.
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