The tag has one job, done in seconds
An ID tag is read by a stranger, often outdoors, often while holding a nervous cat who wants to leave. Everything engraved on it should serve that moment. The essentials are your cat's name, which lets the finder call her something familiar and confirm her identity when you speak, and the phone number you are most likely to answer at any hour. If space allows, add a second number for another household member or a trusted contact, because the first phone can be flat, lost, or out of signal at exactly the wrong moment.
What to leave off, and why
Skip your full home address. On a small cat tag it forces tiny, shallow lettering, it can be hard to read in poor light, and it adds nothing once a finder can phone you. Leave off decorative slogans, jokes, and your cat's breed or description, which the finder can see for themselves. Be cautious with reward offers, which take valuable space and can attract the wrong kind of attention. A tag crowded with small lines gets skimmed or given up on, while a tag with two bold lines gets used. Every character you remove makes the characters that remain easier to read at arm's length.
Short lines that genuinely change a finder's actions
Some extra lines earn their space because they change what a finder does next. Indoor cat tells a neighbor she is lost rather than roaming, so they act instead of assuming she belongs on that street. Needs medicine creates urgency and warns against feeding her casually or waiting until morning. Microchipped tells a finder or clinic that scanning her will confirm her identity and registry contact. Choose at most one or two of these, the ones that are true and most relevant for your cat, and phrase them in plain words a non-cat person understands immediately.
Engraving quality and tag practicalities for cats
Choose deep engraving or clear stamping over light surface printing, which wears smooth against the collar hardware within months. Check the tag under ordinary room light: if you squint, a stranger in rain will not manage. Keep the tag small and light, flat against the collar or in a plate style for a cat bothered by a dangling disc, and use a breakaway collar so the tag never becomes a snag hazard. Recheck the lettering whenever you check the collar fit, and replace the tag the moment a digit becomes ambiguous, since a guessed phone number is no better than none.
When the number or the cat's life changes
Re-engrave after any phone number change, move, or change in who should be called, and treat an outdated tag as worse than a plain one because it sends a finder confidently to the wrong person. Keep a photo of the tag in your phone so lost notices can quote it exactly. The simple tag handles the first minute, while the fuller record behind it handles everything after. That fuller record is her KinsLe Pet Pass, the verified ID card that keeps her identity and your contact details easy to show anywhere.