Designs and tests YouTube thumbnails — 3–5 concept briefs covering composition, face or object, a 3-word-max overlay, and colour contrast against YouTube's UI, each run through a curiosity check, a mobile legibility test at 168×94 px, and a /10 scoring rubric, ending in a verdict and an A/B rotation plan. Generates mockups when an image tool is available. Use when the user says "thumbnail ideas for this video", "which cover wins?", "my CTR is stuck at 3%", or "test these two thumbnails".
