Holdout Validation

Q: What is a Claude Code skill and how does the Holdout Validation skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Holdout Validation is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the General category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: General · Sub-category: general-misc · Last updated: 2026-05-21

type:review

Cross-reference agent self-review claims against actual file state using hidden holdout scenarios, producing mapped P1/P2/P3 findings that reference visible acceptance criteria only. Use when verifying implementation completeness after self-review in start (Phase 4 VERIFY), address (convergence check), or review (parallel fan-out). Also use when an agent claims evidence for a criterion but the file state may not support the claim. This skill MUST be consulted because it detects blind spots in self-review that no other skill catches; a conversational answer cannot systematically test holdout scenarios or cross-reference claims against files.

Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

You are an independent claim verifier — you cross-reference agent self-review claims against actual file state using hidden holdout scenarios that the executing agent never sees. Your core insight: agents often claim "test added for X" or "error handling covers Y" without the claim being true. You verify the claim against the files.

What this skill does

Holdout Validation is a community-contributed Claude Code skill in the general-misc sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/holdout-validation/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when verifying implementation completeness after self-review in start (Phase 4 VERIFY), address (convergence check), or review (parallel fan-out). Also use when an agent claims evidence for a criterion but the file state may not support the claim.

Who uses this skill

The Holdout Validation Claude Code skill is built for Claude Code users and developers across all disciplines looking for general-purpose AI assistance. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 153,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/holdout-validation
curl -L https://claudskills.com/skills/holdout-validation/SKILL.md \
  -o ~/.claude/skills/holdout-validation/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/holdout-validation/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/holdout-validation/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\holdout-validation\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Holdout Validation Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/holdout-validation/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the Holdout Validation skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the Holdout Validation skill?

Use Holdout Validation when your Claude Code task falls under the General category — specifically in the general misc area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Holdout Validation" or describe the task and let Claude pick). Browse related skills at /category/general/.

What is a Claude Code skill and how does the Holdout Validation skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Holdout Validation is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the General category. Learn more at /learn/what-is-a-claude-skill/.

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

ClaudSkills. (2026). Holdout Validation [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/holdout-validation/

BibTeX

@misc{holdout-validation-2026,
  author    = {ClaudSkills},
  title     = {Holdout Validation [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/holdout-validation/}
}

Embed this skill

Promote, attribute, or link this skill from your own README, blog post, or documentation. All three snippets are free to use — no sign-up, no API key. More distribution surfaces →

Badge

[![ClaudSkills](https://claudskills.com/badge/holdout-validation.svg)](https://claudskills.com/skills/holdout-validation/?utm_source=badge&utm_medium=readme&utm_campaign=skill_badge)

Security scan

Grade A · scanned 2026-07-18 — free static scan against the OWASP Agentic Skills Top 10.

No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›

✓ Prompt injection
✓ Data exfiltration
✓ Supply chain
✓ Reverse shell
✓ Credentials
✓ Execution
✓ Filesystem
✓ Persistence
✓ Obfuscation
✓ Network

Show this grade on your repo (click to copy):

[![Security: A](https://img.shields.io/badge/Security-A-2e7d32)](https://claudskills.com/skills/holdout-validation/#security)

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Part of ClaudSkills — the open registry for Claude Skills & Claude Code Skills. · What's New · Install guide · About · llms.txt

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