social-media-image-sizes

social-media-image-sizes is a utility skill that checks and resizes images against the specifications of nine social platforms (Instagram, Facebook, X/Twitter, LinkedIn, TikTok, YouTube, Pinterest, Snapchat, and Threads), covering 60+ named specs. It solves the everyday problem of not knowing whether an image fits a platform slot, or how to export a correctly sized copy, by providing two Node scripts plus detailed per-platform reference documents.

The check script validates an image and outputs a ranked match list (perfect, close, usable, too small) with an inline resize command for every non-perfect match, and supports filtering by platform or match level. The resize script exports a correctly sized copy using the sharp image library, defaulting to a center-crop cover fit with an option to letterbox via contain and a custom background color, and can list all available spec names. The skill bundles reference markdown for each platform plus a compiled AGENTS.md, and documents practical gotchas such as sharp's native binary download, Instagram carousel aspect-ratio consistency, and platform-specific safe zones for Facebook covers and YouTube banners.

It targets social media managers, designers, and marketers preparing assets for posts or ads. Prerequisites are Node.js 18+ and npm (or pnpm) with a one-time install. The scripts operate on local image files using a well-known imaging library and perform only safe, local read/convert operations, with the allowed tool scoped to Bash for running the two scripts.