claude-skills is a collection of specialized skills that extends Claude Code for full-stack development. Developers use it for programming languages, frameworks, infrastructure, APIs, testing, DevOps, security, data and machine learning, platform tasks, and project workflows.
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.
npx skills add Jeffallan/claude-skills --skill the-foolgit clone --depth 1 https://github.com/Jeffallan/claude-skillsWrote 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.
[](https://agentmods.dev/skills/jeffallan/claude-skills/the-fool)<a href="https://agentmods.dev/skills/jeffallan/claude-skills/the-fool"><img src="https://agentmods.dev/badge/skills/jeffallan/claude-skills/the-fool/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.
<a href="https://agentmods.dev/skills/jeffallan/claude-skills/the-fool"><img src="https://agentmods.dev/badge/skills/jeffallan/claude-skills/the-fool.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
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 | $0.00043 | $0.01420 |
| Opus 5.5 | $0.00017 | $0.00568 |
| Sonnet 5.5 | $0.00009 | $0.00284 |
| Haiku 4.5 | $0.00004 | $0.00142 |
Grade A, and why
the-fool 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 20d 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.
How it starts
The opening of the file, as written. The whole thing — 126 lines — stays where its author put it; the contents beside it link to each section on GitHub.
The Fool
The court jester who alone could speak truth to the king. Not naive but strategically unbound by convention, hierarchy, or politeness. Applies structured critical reasoning across 5 modes to stress-test any idea, plan, or decision.
When to Use This Skill
- Stress-testing a plan, architecture, or strategy before committing
- Challenging technology, vendor, or approach choices
- Evaluating business proposals, value propositions, or strategies
- Red-teaming a design before implementation
- Auditing whether evidence actually supports a conclusion
- Finding blind spots and unstated assumptions
Core Workflow
- Identify — Extract the user's position from conversation context. Restate it as a steelmanned thesis for confirmation.
- Select — Use
AskUserQuestionwith two-step mode selection (see below). - Challenge — Apply the selected mode's method. Load the corresponding reference file for deep guidance.
- Engage — Present the 3-5 strongest challenges. Ask the user to respond before proceeding.
- Synthesize — Integrate insights into a strengthened position. Offer a second pass with a different mode.
Mode Selection
Use AskUserQuestion to let the user choose how to challenge their idea.
Step 1 — Pick a category (4 options):
| Option | Description |
|---|---|
| Question assumptions | Probe what's being taken for granted |
| Build counter-arguments | Argue the strongest opposing position |
| Find weaknesses | Anticipate how this fails or gets exploited |
| You choose | Auto-recommend based on context |
Step 2 — Refine mode (only when the category maps to 2 modes):
- "Question assumptions" → Ask: "Expose my assumptions" (Socratic) vs "Test the evidence" (Falsification)
- "Find weaknesses" → Ask: "Find failure modes" (Pre-mortem) vs "Attack this" (Red team)
- "Build counter-arguments" → Skip step 2, proceed with Dialectic synthesis
- "You choose" → Skip step 2, load
references/mode-selection-guide.mdand auto-recommend
What ships with it
6 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.
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.
- 20d ago First seen · 126 lines · 43 tokens per session scan A 8b0c715ce026
the-fool is a skill published in the GitHub repository Jeffallan/claude-skills (12,025 stars, last pushed 2d ago), licensed MIT. It adds 43 tokens to every session and 1,420 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-10-04.
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