skill

skill is a skill for Claude Code, Codex from alessiomarcone/agent-fieldbook. It costs 69 tokens per session (471 once invoked), scanned A, original, MIT.

A workflow for turning a repeated task into one focused, reusable agent skill with clear triggers, inputs, outputs, and checks. It also covers references, validation, and when a skill is not the right form of add-on.

In plain words
What is it for?
Use it to create, revise, split, review, or test SKILL.md workflows for Claude, Codex, or other Agent Skills-compatible systems.
Why use it?
It helps make agent instructions consistent and easier to test. This reduces vague activation rules, oversized workflows, and unclear behavior when something goes wrong.

Skill for Claude CodeCodex

Written for Claude Code and Codex: shipped in a Claude Code plugin, but also agents/openai.yaml present. Also seen: mentions subagents; mentions Codex.

Part of the knowledge-pack plugin — 10 skills shipped together

Good fit Use it to create, revise, split, review, or test SKILL.md workflows for Claude, Codex, or other Agent Skills-compatible systems.

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

Made for: Claude Code, Codex.

Or install knowledge-pack, 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 skill

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/alessiomarcone/agent-fieldbook/skill"><img src="https://agentmods.dev/badge/skills/alessiomarcone/agent-fieldbook/skill.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 471 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 $0.00069 $0.00471
Opus 5 $0.00034 $0.00235
Sonnet 5 $0.00014 $0.00094
Haiku 4.5 $0.00007 $0.00047

Measured 9d ago against content hash 57e54d4220ce, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

skill 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 9d 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.

plugins/knowledge-pack/skills/skill/SKILL.md · 46 lines

What it actually says

Skill

Create a skill around one repeatable user intent and one output contract.

References

Resolve the target product, then read its branch:

  • Claude: references/claude-code-estensioni.md.
  • Codex: references/codex-skills.md.
  • Read references/ai-fluency-4d-corso.md when delegation, discernment, or diligence rules shape the workflow.

Procedure

  1. Confirm the workflow is repeatable and belongs in a skill rather than always-on instructions, a subagent, hook, plugin, or MCP integration.
  2. Define at least three representative triggers and clear non-triggers.
  3. Specify inputs, one primary output, failure behavior, side-effect policy, and success checks.
  4. Keep essential procedure in SKILL.md; place detailed knowledge in directly linked references/; use scripts only for deterministic repeated operations.
  5. Match freedom to risk: guidance for flexible work, templates for repeatable work, scripts for fragile deterministic work.
  6. Follow the selected product's current naming and packaging rules.
  7. Validate structure and forward-test triggers, non-triggers, normal cases, boundaries, and failures.

Output contract

Return:

  1. Decision — why a skill is the right mechanism.
  2. Contract — triggers, non-triggers, inputs, output, failure behavior, and authority.
  3. File tree — only required files.
  4. Implementation — complete files when requested.
  5. Validation — exact checks and forward-test prompts.

Boundaries

  • Do not create an “everything” skill.
  • Do not package or publish a bundle of existing workflows; route distribution work to plugin.
  • Do not duplicate detailed material in both SKILL.md and references.
  • Do not add repository documentation inside a skill folder.
  • Do not claim success before validation and trigger testing.
  • Answer in the user's language.
Files

What ships with it

4 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.

  1. 9d ago First seen · 46 lines · 69 tokens per session scan A 57e54d4220ce

Subscribe to this mod's changes

skill is a skill published in the GitHub repository alessiomarcone/agent-fieldbook (5 stars, last pushed yesterday), licensed MIT. It adds 69 tokens to every session and 471 once invoked, about $0.0003 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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