skill-crafting

skill-crafting is a skill for Claude Code from arvindand/agent-skills. It costs 122 tokens per session (3,421 once invoked), scanned A, original, MIT.

A skill for creating, repairing, checking, and reusing skills—sets of instructions that guide AI agents through specific tasks.

In plain words
What is it for?
Building new skills, fixing skills that do not work, validating or auditing them, checking their character budget, and turning completed work into reusable instructions.
Why use it?
It helps find problems such as unclear instructions, failed triggers, or excessive length before a skill is used in practice.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: reads .claude/ paths; mentions subagents; mentions Claude Code.

Part of the agent-skills plugin — 5 skills shipped together

Good fit Building new skills, fixing skills that do not work, validating or auditing them, checking their character budget, and turning completed work into reusable instructions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/arvindand/agent-skills/skill-crafting
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 arvindand/agent-skills --skill skill-crafting
Clone the repo
git clone --depth 1 https://github.com/arvindand/agent-skills

Made for: Claude Code.

Or install agent-skills, the plugin that ships this one along with the rest of its 5 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 skill-crafting

README.md
[![agentmods](https://agentmods.dev/badge/skills/arvindand/agent-skills/skill-crafting.svg)](https://agentmods.dev/skills/arvindand/agent-skills/skill-crafting)
Your own site
<a href="https://agentmods.dev/skills/arvindand/agent-skills/skill-crafting"><img src="https://agentmods.dev/badge/skills/arvindand/agent-skills/skill-crafting.svg" alt="Measured on agentmods" height="20"></a>
Per session 122 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,421 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
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 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 127
    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 310
    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.
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 $0.00122 $0.03421
Opus 5 $0.00061 $0.01710
Sonnet 5 $0.00024 $0.00684
Haiku 4.5 $0.00012 $0.00342

Measured 8d ago against content hash 356c46858473, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

skill-crafting 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.

The scan reads SKILL.md. This mod also ships 8 executable files (scripts/analyze-all.py, scripts/analyze-compatibility.py, scripts/analyze-cso.py, …), 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/skill-crafting/SKILL.md · 436 lines

How it starts

The opening of the file, as written. The whole thing — 436 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Crafting

Create effective, discoverable skills that work under pressure.

When to Use

Creating:

  • "Create a skill for X"
  • "Build a skill to handle Y"

From Session History:

  • "Create a skill from this session"
  • "Turn what we just did into a skill"
  • "Can the database setup we did become a skill?"
  • "Could we create a skill from this?" (evaluate first)
  • "Should this be a skill?" (evaluate first)

Fixing:

  • "This skill isn't working"
  • "Why isn't this skill triggering?"
  • "Skill didn't trigger when it should have"

Analyzing:

  • "Analyze my skill for issues"
  • "Run skill analysis"
  • "Check this skill's quality"
  • "Audit all my skills"
  • "Check character budget across skills"

Analyzing a Skill

When user asks to analyze a skill:

  1. Run scripts first when available for mechanical checks:

    python3 ${CLAUDE_SKILL_DIR}/scripts/analyze-all.py path/to/skill/
    

    If scripts fail because of environment or tooling issues, state the blocker clearly and continue with manual review.

  2. Read the skill files for qualitative review:

    • Read SKILL.md
    • Read REFERENCES.md (if exists)
    • Read directly linked references/, scripts/, or agents/openai.yaml files when they materially affect behavior
  3. Provide holistic feedback covering:

    • Script results (CSO, structure, tokens) or explicit blocker if scripts could not run
    • Does allowed-tools match what the skill needs to do?
    • Does the analysis cover the files that actually define the skill's behavior?
    • Is the workflow clear and actionable?
    • Are references appropriate and sized correctly?
    • Missing sections or anti-patterns?
  4. Give verdict with prioritized recommendations

Validation Scripts

Script Purpose Usage
analyze-all.py Run all checks python3 ${CLAUDE_SKILL_DIR}/scripts/analyze-all.py path/to/skill/
analyze-cso.py Check CSO compliance python3 ${CLAUDE_SKILL_DIR}/scripts/analyze-cso.py path/to/SKILL.md
analyze-tokens.py Count tokens python3 ${CLAUDE_SKILL_DIR}/scripts/analyze-tokens.py path/to/SKILL.md
analyze-triggers.py Find missing triggers python3 ${CLAUDE_SKILL_DIR}/scripts/analyze-triggers.py path/to/SKILL.md
check-char-budget.py Check description caps python3 ${CLAUDE_SKILL_DIR}/scripts/check-char-budget.py path/to/skills/

Read the full file on GitHub · 436 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 · 436 lines · 122 tokens per session scan A 356c46858473

Subscribe to this mod's changes

skill-crafting is a skill published in the GitHub repository arvindand/agent-skills (16 stars, last pushed 11d ago), licensed MIT. It adds 122 tokens to every session and 3,421 once invoked, about $0.0006 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.