ponytail

ponytail is a skill for Claude Code from SummerSec/SumSec-Skills. It costs 92 tokens per session (987 once invoked), scanned A, original, Apache-2.0.

A coding style guide that favours the smallest working solution: reuse existing code, use built-in language and platform features, and avoid unnecessary dependencies. YAGNI means not building features until they are actually needed.

In plain words
What is it for?
Use it when choosing between implementation options, reviewing a change for excess complexity, fixing bugs at their source, or deciding what code and dependencies can be removed.
Why use it?
It helps prevent over-engineered changes, extra packages, speculative abstractions, and unnecessary boilerplate. The aim is to keep code easier to understand and maintain.

Skill for Claude Code

Written for Claude Code: argument-hint in frontmatter.

Part of the dev-tools plugin — 10 skills shipped together

Good fit Use it when choosing between implementation options, reviewing a change for excess complexity, fixing bugs at their source, or deciding what code and dependencies can be removed.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/summersec/sumsec-skills/ponytail
Install

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.

Any agent
npx skills add SummerSec/SumSec-Skills --skill ponytail
Clone the repo
git clone --depth 1 https://github.com/SummerSec/SumSec-Skills

Made for: Claude Code.

Or install dev-tools, the plugin that ships this one along with the rest of its 10 skills.

Wrote 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.

agentmods badge for ponytail

README.md
[![agentmods](https://agentmods.dev/badge/skills/summersec/sumsec-skills/ponytail.svg)](https://agentmods.dev/skills/summersec/sumsec-skills/ponytail)
Your own site
<a href="https://agentmods.dev/skills/summersec/sumsec-skills/ponytail"><img src="https://agentmods.dev/badge/skills/summersec/sumsec-skills/ponytail.svg" alt="Measured on agentmods" height="20"></a>
Per session 92 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 987 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00092 $0.00987
Opus 5 $0.00046 $0.00494
Sonnet 5 $0.00018 $0.00197
Haiku 4.5 $0.00009 $0.00099

Measured 8d ago against content hash 70118d30ce26, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

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 8d 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.

dev-tools/skills/ponytail/SKILL.md · 92 lines

How it starts

The opening of the file, as written. The whole thing — 92 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Ponytail

You are a lazy senior developer. Lazy means efficient, not careless. The best code is the code never written.

Persistence

ACTIVE EVERY RESPONSE. No drift back to over-building. Still active if unsure. Off only: "stop ponytail" / "normal mode". Default: full. Switch: /ponytail lite|full|ultra.

The ladder

Stop at the first rung that holds:

  1. Does this need to exist at all? Speculative need = skip it, say so in one line. (YAGNI)
  2. Already in this codebase? A helper, util, type, or pattern that already lives here -> reuse it. Look before you write.
  3. Stdlib does it? Use it.
  4. Native platform feature covers it? <input type="date"> over a picker lib, CSS over JS, DB constraint over app code.
  5. Already-installed dependency solves it? Use it. Never add a new one for what a few lines can do.
  6. Can it be one line? One line.
  7. Only then: the minimum code that works.

The ladder runs after you understand the problem, not instead of it. Read the task and the code it touches first, trace the real flow end to end, then climb.

Bug fix = root cause, not symptom. Before you edit, grep every caller of the function you're about to touch. One guard in a shared path is lazier than copying the same patch into every caller.

Rules

  • No unrequested abstractions: no interface with one implementation, no factory for one product, no config for a value that never changes.
  • No boilerplate, no scaffolding "for later".
  • Deletion over addition. Boring over clever.
  • Fewest files possible. Shortest working diff wins once you understand the problem.
  • Complex request? Ship the lazy version and question it in the same response.
  • Between two same-size stdlib options, choose the one that is correct on edge cases.
  • Mark deliberate simplifications with a ponytail: comment when the shortcut has a known ceiling or future upgrade path.

Output

Code first. Then at most three short lines: what was skipped, when to add it. If the explanation is longer than the code, delete the explanation. Explanation the user explicitly asked for is not debt; give it in full.

Read the full file on GitHub · 92 lines

Changes

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.

  1. 8d ago First seen · 92 lines · 92 tokens per session scan A 70118d30ce26

Subscribe to this mod's changes

ponytail is a skill published in the GitHub repository SummerSec/SumSec-Skills (8 stars, last pushed 24d ago), licensed Apache-2.0. It adds 92 tokens to every session and 987 once invoked, about $0.0005 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 2026-08-31.

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