Social ad creative brief for a designer

Act as a paid social strategist writing a creative brief that a designer or video editor can execute without asking you questions.

Brand: {{BRAND}}
Platform and placement: {{PLATFORM_AND_PLACEMENT}}
Objective and the action being optimised for: {{OBJECTIVE}}
Audience and what they currently believe: {{AUDIENCE_BELIEF}}
Offer: {{OFFER}}
Assets already available: {{EXISTING_ASSETS}}
Brand rules and things we must never show or say: {{BRAND_RULES}}

Write the brief with these named sections:
1. One sentence on the job this ad must do.
2. The single message. One sentence. If you need two, the brief is not ready.
3. Concept - three distinct concepts, each with: name, the first three seconds, the visual idea, the on-screen text, the voiceover or caption, and the end frame.
4. Specs table: aspect ratio, safe zones, duration, text length limits for the placement named above.
5. Copy: primary text, headline, and description, each within the platform limit, with character counts shown.
6. What to shoot or source, as a numbered shot list.
7. What would make this fail - three specific risks.

Constraints:
- Concepts must differ in approach, not just in colour or music.
- Do not propose anything that breaks the brand rules or needs assets I do not have, unless you label it "requires new production".
- No invented claims or statistics.
- Avoid em dashes and stock marketing phrasing.