How long should a title and description be?
Google shows roughly 50 to 60 characters of a title and around 150 to 160 of a description before cutting them off, depending on letter widths and screen size. The counters here turn red past those points. Put the important words first, so the start still makes sense if the end is trimmed.
Open Graph and X cards
Facebook, LinkedIn, Slack, Discord, WhatsApp, iMessage and most other apps read Open Graph tags to build link previews. X reads its own twitter: tags and falls back to Open Graph. Use a full https:// address for the share image, at 1200 × 630 pixels, and keep text in the image large because it is often shown small.
Why previews sometimes don’t update
Social networks cache link previews, sometimes for days. After changing your tags, use each network’s own link preview checker to refresh it, and make sure the image address loads without a login or redirect.