Use when auditing Open Graph tags or generating og:image assets. Applies to any page that may be shared on social networks or messaging platforms.
インストールする前に、エージェントに与えられる指示の中身を確認できます。
An incorrectly sized og:image is displayed poorly or not at all on social platforms—Facebook, Twitter/X, LinkedIn each crop or skip images that don't meet their requirements, resulting in blank or distorted link previews.
Find the og:image meta tag in <head> and fetch the image URL. Check the image dimensions and file size. Flag if width < 1200px, height < 630px, aspect ratio differs significantly from 1.91:1, or file size exceeds 5 MB.
Generate or resize the og:image to exactly 1200×630 pixels. Export as JPEG at 80–85% quality to balance visual quality and file size. Reference the absolute HTTPS URL in the og:image meta tag. Add og:image:width and og:image:height tags to help platforms render the image without downloading it first.
Social platforms use og:image to construct the visual card shown when a URL is shared. An image too small may be skipped or shown as a thumbnail. An image with the wrong aspect ratio gets cropped, often cutting off important content. The recommended 1200×630 size ensures optimal display across Facebook, LinkedIn, Slack, and iMessage.
Check the og:image meta tag value. Fetch the image and verify: (1) dimensions are at least 1200×630 px, (2) aspect ratio is approximately 1.91:1, (3) file size is under 5 MB, (4) URL is absolute HTTPS, (5) og:image:width and og:image:height tags match actual dimensions. Flag relative URLs or images smaller than 600×315 px.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/rules/seo/og-image-size
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概要と使いどころ
Use when reviewing templates, rendered HTML, or shared components related to Create a custom 404 error page. Validate the final browser-facing markup, not just the source framework abstraction.
日本語の概要は準備中です。原文の説明を表示しています。
Use when auditing metadata, crawlability, structured data, or indexability related to Create a dedicated About page. Verify the rendered HTML and HTTP response rather than relying only on source files.
日本語の概要は準備中です。原文の説明を表示しています。
Use when reviewing component libraries, page flows, or CI pipelines that need repeatable accessibility checks. Automated testing is strongest at catching structural and attribute-level issues; it does not replace keyboard, screen reader, and manual UX testing.
日本語の概要は準備中です。原文の説明を表示しています。
Use when reviewing sign-in, sign-up, MFA, CAPTCHA, recovery, and re-auth flows. Evaluate the full authentication path, including error handling and backup methods, not just the primary login form.
日本語の概要は準備中です。原文の説明を表示しています。
Use when reviewing templates, rendered HTML, or shared components related to Make notifications accessible. Validate the final browser-facing markup, not just the source framework abstraction.
日本語の概要は準備中です。原文の説明を表示しています。
Use when reviewing rendered HTML, interactive components, or design-system patterns related to Use semantic table markup for screen readers. Check native semantics first, then inspect keyboard behavior, focus flow, accessible names, and screen-reader output where relevant.
日本語の概要は準備中です。原文の説明を表示しています。