agent-skills-creator

agent-skills-creator is a skill for Claude Code, Codex from mblode/agent-skills. It costs 76 tokens per session (2,590 once invoked), scanned A, original, MIT.

A guide for creating and improving agent skills in the open Agent Skills format.

In plain words
What is it for?
Use it to create, audit, rewrite, simplify, validate, and ship skills, including their references, scripts, evaluations, and README updates.
Why use it?
It helps structure skill files and supporting materials consistently, while checking whether their rules are useful and appropriately sized.

Skill for Claude CodeCodex

Written for Claude Code and Codex: ${CLAUDE_SKILL_DIR} variable, but also reads ~/.codex or $CODEX_HOME. Also seen: mentions CLAUDE.md; mentions subagents; mentions Claude Code.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is - **[<skill-name>](./skills/<skill-name>/SKILL.md)**: <one-line description>.

Part of the agent-skills plugin — 25 skills shipped together

Good fit Use it to create, audit, rewrite, simplify, validate, and ship skills, including their references, scripts, evaluations, and README updates.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/mblode/agent-skills
agentmods
npx agentmods add skills/mblode/agent-skills/agent-skills-creator

Made for: Claude Code, Codex.

Or install agent-skills, the plugin that ships this one along with the rest of its 25 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 agent-skills-creator

README.md
[![agentmods](https://agentmods.dev/badge/skills/mblode/agent-skills/agent-skills-creator/github.svg)](https://agentmods.dev/skills/mblode/agent-skills/agent-skills-creator)
Your own site
<a href="https://agentmods.dev/skills/mblode/agent-skills/agent-skills-creator"><img src="https://agentmods.dev/badge/skills/mblode/agent-skills/agent-skills-creator/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.

agentmods 80×15 button for agent-skills-creator

Your own site · 80×15
<a href="https://agentmods.dev/skills/mblode/agent-skills/agent-skills-creator"><img src="https://agentmods.dev/badge/skills/mblode/agent-skills/agent-skills-creator.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 76 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,590 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. Third-party audits
  • Socket pass 17 May 2026
  • Snyk pass 17 May 2026
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 3 findings, up to high

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 →

  • high Rogue Agent · line 50
    Skill modifies its own code, configuration, or behavior at runtime. Self-modification enables an agent to escalate privileges, disable safety constraints, or install persistent backdoors.
    Fix: Prevent the skill from modifying its own code, SKILL.md, or configuration files. Treat skill files as read-only at runtime.
  • high Rogue Agent · line 68
    Skill modifies its own code, configuration, or behavior at runtime. Self-modification enables an agent to escalate privileges, disable safety constraints, or install persistent backdoors.
    Fix: Prevent the skill from modifying its own code, SKILL.md, or configuration files. Treat skill files as read-only at runtime.
  • medium Rogue Agent · line 49
    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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00076 $0.02590
Opus 5 $0.00038 $0.01295
Sonnet 5 $0.00015 $0.00518
Haiku 4.5 $0.00008 $0.00259

Measured 4d ago against content hash 8d076a01dc6e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

agent-skills-creator 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 4d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate.sh), 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.

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.

skills/agent-skills-creator/SKILL.md · 145 lines

How it starts

The opening of the file, as written. The whole thing — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent Skills Creator

Create and improve skills in the Agent Skills open format: full lifecycle from pattern selection through validation and README update.

  • IS: creating new agent skills and auditing or rewriting existing ones: SKILL.md, references, rules folders, scripts, evaluations.
  • IS NOT: AGENTS.md/CLAUDE.md instruction files (use agents-md) or general documentation quality (use docs-writing).

Choose a Mode

  • New skill → Creation Workflow below.
  • Audit, improve, or rewrite an existing skill → references/improving-existing-skills.md, which scores eleven audit dimensions, runs an ordered rewrite, then reuses Steps 5-8 for validation and shipping.
  • Simplify a skill or update a collection → same reference, plus references/capability-delta.md for retention decisions and the collection ledger.
  • Skill never triggers, or triggers on the wrong prompts → the Routing Evals section of references/evaluation-and-iteration.md, then the description. Body edits do not fix routing.

Reference Files

File Read When
references/capability-delta.md Removing generic coaching, evaluating model upgrades, or auditing a whole collection
references/authoring-tips.md Default when writing or cutting body content: judgement over rules, constraint calibration, degrees of freedom, content patterns, descriptions
references/skill-patterns.md Choosing a structural pattern
references/format-specification.md Directory layout, spec versus Claude Code-only frontmatter, body substitutions, loading semantics, which host reads the skill from where and what each can do, naming
references/rules-folder-structure.md Building a rules-based audit/lint skill
references/improving-existing-skills.md Auditing, scoring, simplifying, or rewriting an existing skill
references/executable-code.md Skill includes scripts, injects live context with !, depends on packages, or invokes MCP tools
references/evaluation-and-iteration.md Writing evals/evals.json, routing tests, ablating constraints, testing across models
references/adopt-adapt-author.md A public skill already covers this ground, or deciding whether to vendor, adapt, or replace a third-party skill

Read the full file on GitHub · 145 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. 4d ago Changed · -8 lines · -106 tokens per session scan B → A 8d076a01dc6e
  2. 10d ago First seen · 153 lines · 182 tokens per session scan B dc8228574eff

Subscribe to this mod's changes

agent-skills-creator is a skill published in the GitHub repository mblode/agent-skills (106 stars, last pushed 2d ago), licensed MIT. It adds 76 tokens to every session and 2,590 once invoked, about $0.0004 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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