Success Criteria Guide

Why Success Criteria Matter

Without clear criteria:

• Workers don't know when they're "done"
• Verification is subjective
• Evidence collection is impossible

With clear criteria:

• Binary pass/fail determination
• Automated verification possible
• Evidence is specific and actionable

SMART Criteria

Property	Description	Example
Specific	Exactly what must happen	"POST /api/users returns 201"
Measurable	Can be verified	"Test coverage > 80%"
Achievable	Actually possible	Not "zero bugs forever"
Relevant	Relates to the goal	Not "code is pretty"
Testable	Can prove it	Command/test that verifies

Criteria Templates

API Endpoint

Success Criteria:
- Endpoint responds with 200 for valid input
- Returns expected JSON schema
- Returns 400 for invalid input with error message
- Returns 401 for unauthenticated requests

Evidence: curl commands or test output

Database Change

Success Criteria:
- Migration runs without error
- Rollback works without error
- Existing data is preserved
- New queries execute correctly

Evidence: Migration output, query results

UI Component

Success Criteria:
- Component renders without console errors
- Handles loading state
- Handles error state
- Handles empty state
- Passes accessibility checks

Evidence: Test output, screenshot

Performance Optimization

Success Criteria:
- Response time reduced from Xms to <Yms
- Memory usage stays under Zmb
- No regression in functionality

Evidence: Benchmark before/after

Bug Fix

Success Criteria:
- Failing test now passes
- Original issue no longer reproducible
- No new test failures introduced

Evidence: Test output, reproduction steps

Refactoring

Success Criteria:
- All existing tests pass
- No behavior changes
- Code complexity reduced (if measurable)

Evidence: Test output, complexity metrics

Evidence Formats

Type	When to Use	Example
Test output	Automated tests exist	npm test exit code 0
Command output	CLI verification	curl -I /api/health → 200
Screenshot	Visual verification	UI renders correctly
Metrics	Performance	Before: 2s, After: 200ms
Logs	Runtime behavior	No errors in logs

Anti-Patterns

Too Vague

❌ "It works"
❌ "Code is clean"
❌ "User can login"

✅ "POST /login returns JWT token"
✅ "No ESLint errors"
✅ "Login test passes with valid credentials"

Unmeasurable

❌ "Performance is better"
❌ "UX is improved"

✅ "Page load < 2s on 3G"
✅ "User can complete checkout in < 5 clicks"

Too Many Criteria

❌ 20 criteria for one task (task too big)
✅ 2-5 criteria per task, split if more needed

Verification Checklist

Before finalizing success criteria, ask:

1. Can a worker know exactly when they're done?
2. Can evidence be collected automatically or easily?
3. Is there a single source of truth (test, command, metric)?
4. Would two people agree on pass/fail?