Agent skill
devils-advocate
Use when challenging assumptions, surfacing risks, or stress-testing designs and decisions. Triggers: 'challenge this', 'play devil's advocate', 'what could go wrong', 'poke holes', 'find the flaws', 'what am I missing', 'is this solid', 'red team this', 'what are the weaknesses', 'risk assessment', 'sanity check'. Works on design docs, architecture decisions, or any artifact needing adversarial review.
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/devils-advocate-axiomantic-spellbook
SKILL.md
Invariant Principles
- Untested assumptions become production bugs. Every claim needs evidence or explicit "unvalidated" flag.
- Vague scope enables scope creep. Boundaries must be testable, not interpretive.
- Optimistic architecture fails at scale. Every design decision needs "what if 10x/failure/deprecated" analysis.
- Undocumented failure modes become incidents. Every integration needs explicit failure handling.
- Unmeasured success is unfalsifiable. Metrics require numbers, baselines, percentiles.
Applicability
| Use | Skip |
|---|---|
| Understanding/design doc complete | Active user discovery |
| "Challenge this" request | Code review (use code-reviewer) |
| Before architectural decision | Implementation validation (use fact-checking) |
Inputs
| Input | Required | Description |
|---|---|---|
document_path |
Yes | Path to understanding or design document to review |
focus_areas |
No | Specific areas to prioritize (e.g., "security", "scalability") |
known_constraints |
No | Constraints already accepted (skip challenging these) |
Outputs
| Output | Type | Description |
|---|---|---|
review_document |
Inline | Structured review following Output Format template |
issue_count |
Inline | Summary counts: critical, major, minor |
readiness_verdict |
Inline | READY, NEEDS WORK, or NOT READY assessment |
Review Protocol
Required Sections (flag missing as CRITICAL)
Problem statement, research findings, architecture, scope, assumptions, integrations, success criteria, edge cases, glossary.
Challenge Categories
| Category | Classification | Challenges |
|---|---|---|
| Assumptions | VALIDATED/UNVALIDATED/IMPLICIT/CONTRADICTORY | Evidence sufficient? Current? What if wrong? What disproves? |
| Scope | Vague language? Creep vectors? | MVP ship without excluded? Users expect? Similar code supports? |
| Architecture | Rationale specific or generic? | 10x scale? System fails? Dep deprecated? Matches codebase? |
| Integration | Interface documented? Stable? | System down? Unexpected data? Slow? Auth fails? Circular deps? |
| Success Criteria | Has number? Measurable? | Baseline? p50/p95/p99? Monitored how? |
| Edge Cases | Boundary, failure, security | Empty/max/invalid? Network/partial/cascade? Auth bypass? Injection? |
| Vocabulary | Overloaded? Matches code? | Context-dependent meanings? Synonyms to unify? Two devs interpret same? |
Fractal exploration (optional): When any finding is classified as CRITICAL, invoke fractal-thinking with intensity pulse and seed: "What are the second-order consequences if [critical issue] is not addressed?". Use the synthesis to add depth to CRITICAL findings with impact chains.
Challenge Template
[ITEM]: "[quoted from doc]"
- Classification: [type]
- Evidence: [provided or NONE]
- What if wrong: [failure impact]
- Similar code: [reference or N/A]
- VERDICT: [finding + recommendation]
Output Format
# Devil's Advocate Review: [Feature]
## Executive Summary
[2-3 sentences: critical count, major risks, overall assessment]
## Critical Issues (Block Design Phase)
### Issue N: [Title]
- **Category:** [from challenge categories]
- **Finding:** [what is wrong]
- **Evidence:** [doc sections, codebase refs]
- **Impact:** [what breaks]
- **Recommendation:** [specific action]
## Major Risks (Proceed with Caution)
### Risk N: [Title]
[Same format + Mitigation]
## Minor Issues
- [Issue]: [Finding] -> [Recommendation]
## Validation Summary
| Area | Total | Strong | Weak | Flagged |
|------|-------|--------|------|---------|
| Assumptions | N | X | Y | Z |
| Scope | N | justified | - | questionable |
| Architecture | N | well-justified | - | needs rationale |
| Integrations | N | failure documented | - | missing |
| Edge cases | N | covered | - | recommended |
## Overall Assessment
**Readiness:** READY | NEEDS WORK | NOT READY
**Confidence:** HIGH | MEDIUM | LOW
**Blocking Issues:** [N]
Self-Check
<FINAL_EMPHASIS> Every passed assumption = production bug. Every vague requirement = scope creep. Every unexamined edge case = 3am incident. Thorough. Skeptical. Relentless. </FINAL_EMPHASIS>
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