Agent skill
reviewing-design-docs
Use when reviewing design documents, technical specifications, architecture docs, RFCs, ADRs, or API designs for completeness and implementability. Triggers: 'review this design', 'is this spec complete', 'can someone implement from this', 'what's missing from this design', 'review this RFC', 'is this ready for implementation', 'audit this spec'. Core question: could an implementer code against this without guessing?
Install this agent skill to your Project
npx add-skill https://github.com/axiomantic/spellbook/tree/main/skills/reviewing-design-docs
SKILL.md
Invariant Principles
- Specification sufficiency determines implementation success. Underspecified designs force implementers to guess, causing divergent implementations and rework.
- Method names are suggestions, not contracts. Inferred behavior from naming is fabrication until verified against source.
- Vague language masks missing decisions. "Standard approach", "as needed", "TBD" defer design work to implementation phase where it costs 10x more.
- Complete != comprehensive. Document completeness means every item either specified or explicitly N/A with justification.
Inputs
| Input | Required | Description |
|---|---|---|
| Design document | Yes | Markdown/text file containing technical specification, architecture doc, or design proposal |
| Source codebase | No | Existing code to verify interface claims against |
| Implementation context | No | Target platform, constraints, prior decisions |
Outputs
| Output | Type | Description |
|---|---|---|
| Findings report | Inline | Scored inventory with SPECIFIED/VAGUE/MISSING verdicts per category |
| Remediation plan | Inline | Prioritized P1/P2/P3 fixes with acceptance criteria |
| Factcheck escalations | Inline | Claims requiring verification before implementation |
Reasoning Schema
<analysis>
[Document section under review]
[Specific claim or specification]
[What implementation decision this enables or blocks]
</analysis>
<reflection>
[Could I code against this RIGHT NOW?]
[What would I have to invent/guess?]
[Verdict: SPECIFIED | VAGUE | MISSING]
</reflection>
Example verdict: "Authentication timeout: 30s" → SPECIFIED. "Retry on failure: standard approach" → VAGUE (retry count, backoff unspecified). "Rate limiting" → MISSING (no mention).
Phase 1: Document Inventory
## Sections: [name] - lines X-Y
## Components: [name] - location
## Dependencies: [name] - version: Y/N
## Diagrams: [type] - line X
Phases 2-3: Completeness Checklist + Hand-Waving Detection
Evaluate every category for specification completeness. Detect vague language, assumed knowledge, and magic numbers.
Execute: /review-design-checklist
Outputs: Completeness matrix with SPECIFIED/VAGUE/MISSING verdicts, vague language inventory, assumed knowledge list, magic number list
Optional deep audit: For specs with 3+ VAGUE items, run /sharpen-audit on specific sections to get executor-prediction analysis (what an implementer would guess for each ambiguity).
Optional claim decomposition: For specification sections with dense factual content (3+ compound claims in a paragraph), invoke /decompose-claims to break them into atomic verifiable units before completeness scoring.
Phases 4-5: Interface Verification + Implementation Simulation
Verify all interface claims against source code. Escalate unverifiable claims to factchecker. Simulate implementation per component to surface gaps.
Execute: /review-design-verify
Outputs: Verification table, factchecker escalations, per-component implementation simulation
Phases 6-7: Findings Report + Remediation Plan
Compile scored findings report and prioritized remediation plan.
Execute: /review-design-report
Outputs: Score table, numbered findings with location and remediation, P1/P2/P3 remediation plan with factcheck and additions sections
Self-Check
[ ] Full document inventory
[ ] Every checklist item marked
[ ] All vague language flagged
[ ] Interfaces verified (source read, not assumed)
[ ] Claims escalated to factchecker
[ ] Implementation simulated per component
[ ] Every finding has location + remediation
[ ] Prioritized remediation complete
<FINAL_EMPHASIS> NOT "does this sound reasonable?"
"Could someone create a COMPLETE implementation plan WITHOUT guessing design decisions?"
For EVERY specification: "Is this precise enough to code against?"
If uncertain: under-specified. Find it. Flag it. </FINAL_EMPHASIS>
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