What is skill-hygiene?

A governance and maintenance guide for reviewing locally installed agent skills and deciding whether they are stale, broken, conflicting, or safe to retire.

Auditing skill installations, assessing quality and risks, reviewing cleanup or migration options, and planning quarantine or upgrades when the evidence supports them.

It helps manage skill sprawl while accounting for symlinks, which are links used to make one installed skill available to several agents rather than duplicate copies. It uses collected evidence and recommends caution when the situation is unclear.

skill-hygiene — Skill for Claude Code and Codex by yknothing

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 yknothing/skills-refiner --skill skill-hygiene

Clone the repo

git clone --depth 1 https://github.com/yknothing/skills-refiner

Made for: Claude Code, Codex.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/yknothing/skills-refiner/skill-hygiene/github.svg)](https://agentmods.dev/skills/yknothing/skills-refiner/skill-hygiene)

Your own site

<a href="https://agentmods.dev/skills/yknothing/skills-refiner/skill-hygiene"><img src="https://agentmods.dev/badge/skills/yknothing/skills-refiner/skill-hygiene/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/yknothing/skills-refiner/skill-hygiene"><img src="https://agentmods.dev/badge/skills/yknothing/skills-refiner/skill-hygiene.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 64 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 4,612 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 5 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

medium Agent Snooping · line 14
Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.

Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
medium Privilege Escalation · line 64
Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.

Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
medium Privilege Escalation · line 361
Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.

Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
medium Rogue Agent · line 100
Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.

Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
medium Rogue Agent · line 380
Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.

Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00064	$0.04612
Opus 5.5	$0.00026	$0.01845
Sonnet 5.5	$0.00013	$0.00922
Haiku 4.5	$0.00006	$0.00461

Measured 2mo ago against content hash b8e596d257b3, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

skill-hygiene scanned grade A with 1 finding 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 2mo ago.

The scan reads SKILL.md. This mod also ships 37 executable files (bin/skill-scan.sh, lib/cleanup-cli.mjs, lib/cleanup-contract.mjs, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Asks for rootlowPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

chmod 700 "$SESSION_DIR" || { rmdir -- "$SESSION_DIR"; exit 1; }

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

skills/skill-hygiene/SKILL.md · 350 lines

How it starts

The opening of the file, as written. The whole thing — 350 lines — stays where its author put it; the contents beside it link to each section on GitHub.

skill-hygiene

You are a senior agent-skills governance advisor. Your role is to help users understand the health and quality of their installed skills, identify risks, and recommend improvements — with judgment, not rote rules.

Philosophy

AI judges, scripts collect. The shell script (bin/skill-scan.sh) gathers structured facts. You interpret those facts using your expertise, the user's context, and your understanding of skill design quality.
Conservative by default. If you are not confident that something is broken or harmful, do NOT recommend removal. Flag it as an observation or advisory warning. Only recommend action when the evidence is clear.
Respect the topology. Skills installed via npx/npm to ~/.agents/skills/ and symlinked to agent directories (.claude/skills/, .cursor/skills/, .codex/skills/, etc.) are the standard installation pattern. Symlinks are NOT duplicates — they are distribution links.
Scope matters. Only skills in agent-recognized directories (~/.<agent>/skills/) are "active". Start with the compatibility roots, then fresh-discover exact immediate home paths matching ~/.<agent>/skills; do not assume an old static root list is complete. Standalone Git repos or project directories elsewhere on disk are independent codebases — do not treat them as broken or misplaced skills.

Running tools from an agent session

When you have shell access and the user asks for a skills health check, inventory, or governance triage (without insisting on paste-only mode):

Prefer running the self-contained, read-only skill-scan.sh collector directly instead of asking the user to copy-paste output — unless the environment forbids shell execution or the user opts out.
Use skills-refiner-doctor.sh, skill-probe.sh, or skill-dashboard.sh only when skill-debug is also installed. skill-hygiene does not require skill-debug for its own scan.
Never run skill-trace.sh --inject, --inject-dir, --strip, or --strip-dir without explicit user confirmation (those modify SKILL.md files on disk).

Read the full file on GitHub · 350 lines

Files

What ships with it

42 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

2mo ago Changed · +44 lines b8e596d257b3
2mo ago Changed · -259 lines 2ccac2940979
2mo ago First seen · 565 lines · 64 tokens per session scan A 9b70a16689ce

Subscribe to this mod's changes

skill-hygiene is a skill published in the GitHub repository yknothing/skills-refiner (24 stars, last pushed 1mo ago), licensed MIT. It adds 64 tokens to every session and 4,612 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 1 finding (asks for root). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Building agents

skill-hygiene next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
skill-hygieneyknothing/skills-refiner	Skill	24	1mo ago	MIT	A	64	Claude Code, Codex
imagegenopenai/codex	Skill	135k	today	Apache-2.0	A	113	Codex
playwright-climicrosoft/playwright	Skill	100k	today	Apache-2.0	A	19	Claude Code
browser-automationopenclaw/openclaw	Skill	394k	today	MIT	A	36	Claude Code
local-ai-agentsmicrosoft/ai-agents-for-beginners	Skill	80k	6d ago	MIT	A	200	Claude Code, Codex
next-cache-components-adoptionvercel/next.js	Skill	143k	today	MIT	A	95	Claude Code
chat-pet-sprite-creationmicrosoft/vscode	Skill	195k	today	MIT	A	53	Claude Code, Codex

skill-hygiene

Getting it into your agent

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Asks for rootlowPrivilege escalation

How it starts

skill-hygiene

Philosophy

Running tools from an agent session

What ships with it

What this file has done since we first saw it

skill-hygiene compared with skills from other repositories