fal.ai Prompting

Runtime: All endpoint calls run via the genmedia CLI. See the genmedia skill for command syntax; run genmedia init once if not yet installed.

Model families have meaningful prompting nuances. A prompt that works on GPT Image 2 (long, structured, exact text in quotes) will fail on Happy Horse (which wants ~20 plain-English words). This skill collects family-specific guides.

When to load which reference

Reference	Load when
kling.md	Working with Kling video models (O3, v3), multi-prompt, element controls, Standard vs Pro tier
gpt-image-2.md	Working with openai/gpt-image-2 or /edit, structured prompts, EXACT TEXT, multi-image compositing
happy-horse.md	Working with alibaba/happy-horse/text-to-video or image-to-video, brevity-first, camera language

Universal principles (all families)

1. Visual facts beat prestige adjectives. Replace "stunning, cinematic, masterpiece" with "overcast daylight, brushed aluminum, 50mm feel."
2. Style tags need visual targets. "Minimalist brutalist" → "cream background, heavy black sans serif, asymmetrical type block, generous negative space."
3. One controlled variable per iteration. Comparison only works when one axis changes at a time.
4. Inspect schema before assuming a control exists. genmedia schema <endpoint_id> --json. Negative prompt, seed, multi-prompt, and reference-image fields differ across families.
5. Per-family rules override universal advice. Happy Horse rejects what GPT Image 2 rewards.

Catalog cross-reference

For "which model do I use" questions, see fal-models-catalog:

• Text-to-image endpoint selection → fal-models-catalog/references/text-to-image.md
• Text-to-video endpoint selection → fal-models-catalog/references/text-to-video.md
• Image-to-video endpoint selection → fal-models-catalog/references/image-to-video.md