# Requirements Definition

> This skill should be used when the user asks to "define requirements", "create specification", "clarify requirements", "write requirements document", or mentions requirement analysis. Provides comprehensive requirements definition methodology. Use when this capability is needed.

- Skill: `tomevault-io/requirements-definition-2` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/requirements-definition-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/requirements-definition-2/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/requirements-definition-2

---


# Requirements Definition

Methodology for requirements definition ensuring comprehensive specification before implementation.

## Investigation Workflow

1. **Directory structure** - Glob
2. **Symbol analysis** - get_symbols_overview
3. **Keyword search** - Grep or find_symbol
4. **Dependency mapping** - find_referencing_symbols
5. **Specific content** - Read
6. **Latest API docs** - Context7

## Question Scoring

Score each unclear requirement (1-5 each):

| Criterion | Description |
|-----------|-------------|
| Design Branching | How much does answer affect design? |
| Irreversibility | How difficult to change after implementation? |
| Investigation Impossibility | Cannot determine through code alone? |
| Effort Impact | How much affects implementation effort? |

**Critical questions (score >= 15)**: Must answer before proceeding.

**Example:**
```
Question: "Should we use TypeScript's strict mode?"
- Design Branching: 5
- Irreversibility: 4
- Investigation Impossibility: 3
- Effort Impact: 4
Total: 16 (critical)
```

## Question Types

- **Spec confirmation**: "Does API return null or empty array?"
- **Design choice**: "REST or GraphQL?"
- **Constraint**: "Must support IE11?"
- **Scope**: "Include admin features in v1?"
- **Priority**: "Which feature first?"

## Functional Requirements Format

```
FR-001: User Authentication
Priority: mandatory
- Users can log in with email/password
- Session expires after 24h inactivity
- Failed logins rate-limited (max 5/hour)
```

## Non-Functional Requirements

```
Performance:
- API response < 200ms (95th percentile)
- Support 1000 concurrent users

Security:
- AES-256 encryption at rest
- JWT authentication

Maintainability:
- Test coverage >= 80%
- Documentation for public APIs
```

## Technical Specifications

```
Design Decision: Use React Query for data fetching
Rationale:
- Built-in caching
- Auto background refetching
- TypeScript support
- Widely adopted in codebase

Impact: All API-calling components, test utilities
```

## Quality Metrics

| Metric | 90-100 | 70-89 | 50-69 | <50 |
|--------|--------|-------|-------|-----|
| Feasibility | Straightforward | Some research | Challenges | Architecture changes |
| Objectivity | All verified | Most verified | Mixed | Mostly assumptions |

## Output Structure

1. **Summary**: Request, background, expected outcomes
2. **Current State**: System, stack, patterns
3. **Functional Requirements**: FR-XXX with priority and acceptance criteria
4. **Non-Functional**: Performance, security, maintainability
5. **Technical Specs**: Design decisions with rationale
6. **Metrics**: Feasibility and objectivity scores
7. **Constraints**: Technical and operational
8. **Test Requirements**: Coverage, scenarios, acceptance
9. **Task Breakdown**: Dependencies, phases, handoff

## Best Practices

**Critical:**
- Investigate current state before defining requirements
- Score questions and prioritize high-score (>= 15)
- Distinguish mandatory from optional with rationale

**High:**
- Document all assumptions when unclear
- Map requirements to test scenarios
- Include rationale for design decisions

## Anti-Patterns

| Avoid | Instead |
|-------|---------|
| Vague requirements | Specific, testable with acceptance criteria |
| Implementation details | Describe what, not how |
| Skipping investigation | Always investigate first |
| Missing constraints | Document all constraints |
| Undefined priorities | Mark mandatory/optional |

## Constraints

**Must:**
- Investigate before concluding
- Ask questions before assuming
- Include (Recommended) option in AskUserQuestion

**Avoid:**
- Proceeding without answering critical questions
- Justifying user preferences over technical validity

---
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<!-- tomevault:4.0:skill_md:2026-04-13 -->