Connect your AI agent to Thumbly with MCP
Thumbly exposes an MCP server so Cursor, Claude Desktop, and other agents can generate, edit, analyze, and score thumbnails with a tb_live_ API key. Setup, tools, limits, and a Grok Bot follow-up example.
Thumbly exposes an MCP server so Cursor, Claude Desktop, and other agents can generate, edit, analyze, and score thumbnails with a tb_live_ API key. Setup, tools, limits, and a Grok Bot follow-up example.
Yes, you can set a custom thumbnail on a YouTube Short. Here's how on Studio and mobile, what size to use, and how to fix a cropped or wrong-ratio cover.
Change a regular video thumbnail in the YouTube Studio app: Content, pencil, Edit thumbnail, Custom. Verify if Custom is missing. Stay under 2MB on mobile.
Change a long-form thumbnail in YouTube Studio on desktop: Content, Details, Upload file, SAVE. Same after publish. Verify if Upload file is missing.
YouTube Studio puts thumbnail CTR on the Reach tab of a video. Content, then Analytics, then Reach. Here's the exact tap path.
Grab any public video’s thumbnail JPG from YouTube’s image CDN. Pull the 11-char video ID, open maxresdefault, Save. Fall back to hqdefault if maxres is gray.
Most guides on this skip the part that matters and send you straight to a sketchy website. Here's the honest version: what you're actually allowed to download, and the methods worth using, from your own footage to Creative Commons to yt-dlp.
Verify the channel at youtube.com/verify so Upload file shows up under Thumbnail. That unlocks the control. It does not upload the image.
Drop a custom long-form thumbnail in YouTube Studio on desktop: Content, Details, pick an auto-generated frame, SAVE. There is no Delete button.
Thumbly Score rates a thumbnail 0 to 100 on virality, clarity, idea, curiosity, and emotion, then hands you three fixes. Here's how to run it on yours before you post.
Instagram Reels covers are 1080 × 1920 (9:16) in the player, but your profile grid crops them to a 1:1 square. Here's how to design one cover that works in both.
One chart with the exact thumbnail and cover size for YouTube, Shorts, TikTok, Instagram, and Facebook in 2026, plus a link to the full guide for each platform.
Same clip, two surfaces. Where the image actually appears, and when to use a custom cover vs a frame.
TikTok covers are 1080 × 1920 (9:16), but the username, caption, and buttons sit on top of them. Here's where to keep your text so it doesn't get buried.
Shorts get custom thumbnails now. The right size is 1080 × 1920 (9:16), not the 16:9 you use for long-form. Here's why that matters and how to add one.
YouTube's native Test & Compare picks a winner by watch time share, not CTR alone. Here's how to run a thumbnail A/B test in Studio, what's eligible, and how to read the result.
Most thumbnail idea lists are moodboards. This one breaks down the patterns behind high-performing YouTube thumbnails by niche — and what to steal from each.
YouTube paints a duration badge, a progress bar, and a tighter mobile crop over your thumbnail. Keep faces and text in the center, and leave the bottom-right empty.
The YouTube thumbnail size is 1280 × 720 at 16:9, and in 2026 YouTube started recommending up to 4K. Here's the full spec, what changed, and the size that matters more than the resolution.