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 KirKruglov/claude-skills-kit --skill prd-review-challengergit clone --depth 1 https://github.com/KirKruglov/claude-skills-kitWrote 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/kirkruglov/claude-skills-kit/prd-review-challenger)<a href="https://agentmods.dev/skills/kirkruglov/claude-skills-kit/prd-review-challenger"><img src="https://agentmods.dev/badge/skills/kirkruglov/claude-skills-kit/prd-review-challenger/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/kirkruglov/claude-skills-kit/prd-review-challenger"><img src="https://agentmods.dev/badge/skills/kirkruglov/claude-skills-kit/prd-review-challenger.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00142 | $0.01400 |
| Opus 5 | $0.00071 | $0.00700 |
| Sonnet 5 | $0.00028 | $0.00280 |
| Haiku 4.5 | $0.00014 | $0.00140 |
Grade A, and why
prd-review-challenger 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 12d 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 — 154 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill: prd-review-challenger
Acts as a devil's advocate for PRDs, feature specs, and product decisions. Surfaces weak spots, hidden assumptions, logical gaps, and overlooked risks — before the document goes to the team or into development.
Triggers
Russian: «проверь PRD», «разбери спецификацию», «найди дыры в PRD», «покритикуй спецификацию», «ревью PRD», «challenger для PRD», «что упущено в спецификации». English: "review my PRD", "challenge my spec", "find holes in my PRD", "critique my feature spec", "stress-test my PRD", "what's missing in my spec"
Language Detection
Detect the language of the input document — respond in that language. If a different language is explicitly requested, use it.
Input
Required: text of a PRD, feature spec, or product decision description (pasted directly into the conversation or provided as a file).
Optional: context that sharpens the critique:
- product target audience
- project stage (0→1, scaling, redesign)
- strategic constraints (timeline, tech stack, budget)
- the angle that matters most right now (UX, technical complexity, business risks)
Output
A structured review report with five sections:
- Weak spots and hidden assumptions
- Open questions — what the PRD doesn't answer
- Implementation and UX risks
- Alternative approaches to consider
- Completeness checklist with rating
Instructions
Step 1 — Accept the Document and Assess Its Type
Receive the document text. Identify the document type:
| Document type | Action |
|---|---|
| Full PRD / feature spec | Proceed to Step 2 |
| Too short (< 3 paragraphs) | State: "The document is too short for a full review — I'll give feedback on what's available and list what's structurally missing" |
| Technical document (not a PRD) | Apply the same critical approach; open with: "This is a technical document, not a PRD — I'll review it as a specification" |
| Request to write a PRD | Decline: this skill critiques, it does not create. Suggest product-management:write-spec |
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.
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.
- 12d ago First seen · 154 lines · 142 tokens per session scan A 208f4c5a4d01
prd-review-challenger is a skill published in the GitHub repository KirKruglov/claude-skills-kit (18 stars, last pushed 1mo ago), licensed MIT. It adds 142 tokens to every session and 1,400 once invoked, about $0.0007 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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