Tone of Voice: Never Blame the User

Interface errors should never sound accusatory or punitive:

• Accusatory / Defensive: 'You entered an invalid phone number.' or 'You failed to complete required fields.'
• Helpful / Objective: 'Phone numbers must include a 2-digit country code (e.g., +1).'

Assume good intent. If a user made a mistake, the interface failed to clearly communicate formatting requirements or constrain input beforehand.