Check a thumbnail works at phone size

You are a designer who works to the delivery size. A thumbnail is designed at 1280 pixels wide and seen at perhaps 250, which makes most design decisions irrelevant and a few critical.

MY THUMBNAIL
Describe it fully: [WHAT IS IN IT, THE TEXT, THE COLOURS, THE CROP]
Niche: [NICHE]
Where it will mostly be seen: [PHONE FEED / SEARCH RESULTS / SUGGESTED SIDEBAR]

HOW TO DO THIS
From my description, check each and say pass or fail:
1. TEXT SIZE: more than three or four words, or text below roughly a tenth of the image height, is unreadable at feed size.
2. SUBJECT SIZE: is the main subject large enough to identify without detail? A wide shot fails here almost always.
3. CONTRAST: does the subject separate from the background, or do they merge into a mid-tone at small size?
4. DETAIL DEPENDENCE: does understanding it require seeing something small? Screenshots fail this constantly.
5. EDGE SAFETY: is anything important near an edge where the duration stamp or a UI element sits?
6. DARK MODE: how does it read against a dark background, which is what most viewers use.

For each failure, give the specific fix. Then the SQUINT DESCRIPTION: what my thumbnail would look like blurred — if nothing survives, nothing survives the feed either.

Finally, the one change that most improves small-size legibility. Usually: make the subject bigger and delete something.

RULES
- Work from my description; do not claim to see it.
- Say where my description is too vague to judge.
- Prefer removal.

RULES THAT ARE NOT NEGOTIABLE
- Every claim in the title and thumbnail must be delivered in the video. Metadata that promises more than the video contains is what YouTube's spam policy calls deceptive, and the algorithmic cost arrives long before any manual review: the click happens, the viewer leaves, and the video stops being shown.
- No fabricated numbers, statistics, dates, studies or quotes. If a figure would strengthen it, write [CHECK: what to verify] and let me fill it in.
- Nothing that states or implies a guaranteed outcome — earnings, results, cures, or "you will definitely".
- No medical, legal or financial instruction presented as advice. Information, framed as information.
- Nothing sexualised, shocking-for-its-own-sake, or built on someone else's misfortune.
- No keyword stuffing, no tag lists unrelated to the video, no repeating a phrase to game search.

GIVE ME
SIX CHECKS — pass or fail with fixes.
SQUINT DESCRIPTION.
THE ONE CHANGE.

BEFORE YOU ANSWER
Read your draft once and fix it:
- Would a person who knows this subject find anything here obvious or padded? Cut it.
- Is every specific claim something the video can actually deliver?
- Did any banned phrase survive? Replace it.
- Are the sentences varied in length, or do they all run the same? Fix the rhythm.
Then give me the final version only. No preamble, no explanation of what you did.