Here are a few options for descriptions, catering to different purposes:

**Option 1: Short & Sweet (Best for general use)**

* **Description:** 往返旅遊的機票，包括去程和回程。 (Wǎngfǎn lǚyóu de jīpiào, bāokuò qùchéng hé huíchéng.) – *Round-trip flight tickets, including outbound and inbound journeys.*

**Option 2: More Informative (Good for clarity)**

* **Description:** 涵蓋目的地來回的機票，通常指一次旅行的整體機票費用。 (Hángài mùdìdì láihuí de jīpiào, tōngcháng zhǐ yīcì lǚxíng de zhěngtǐ jīpiào fèiyòng.) – *Covers round-trip tickets to a destination, usually referring to the overall ticket cost for a single trip.*

**Option 3: Focus on Search Optimization (Includes related keywords)**

* **Description:** 訂購「來回機票」 – 往返機票、國際機票、國內機票，適合旅遊規劃、度假行程，輕鬆安排往返交通。 (Dìnggòu “láihuí jīpiào” – wǎngfǎn jīpiào, guójì jīpiào, guónèi jīpiào, shìhé lǚyóu guīhuà, dùjià xíngchéng, qīngsōng ānpái wǎngfǎn jiāotōng.) – *Book “Round-trip tickets” – return tickets, international flights, domestic flights, suitable for travel planning, vacation itineraries, easily arrange round-trip transportation.*

**Option 4: Concise and Direct**

* **Description:** 往返的飛機票。 (Wǎngfǎn de fēijī piào.) – *Round-trip plane tickets.*

**Which to choose?**

* **If you expect users to find this tag in your site’s search suggestions:** Option 3 is best.
* **If you want a clear and concise explanation:** Option 1 or 4 is good.
* **If you want to give slightly more context:** Option 2 is preferable.

**Important Consideration for WordPress:**

* In WordPress, post tag descriptions are generally used as meta descriptions. Keep them relatively short (ideally under 160 characters) to avoid truncation in search results.
* Keywords are important, but don’t stuff them unnaturally. Write naturally and try to include relevant terms.
* If your theme doesn’t display tag descriptions, they may still be used by search engines to understand the content of the pages that use this tag.

I recommend using Option 1 or 4 as a starting point, adjusting it as needed to include a few relevant keywords (like “travel”, “flights”, etc) if it applies better to your site’s theme and content. Then, you can also choose Option 2 or 3 to provide more detailed information in other related areas or sections of your website.