Here are a few options for a WordPress post tag description in Traditional Chinese, with varying levels of detail and focus, suitable for the title “多久有效” (Duo Jiu You Xiao – meaning “How long is it effective/valid?”):

**Option 1: Concise & General**

> 我們會定期更新關於「多久有效」的詳情，包括產品、服務和資訊。

* **Translation:** We will regularly update details regarding “How long is it valid,” including products, services, and information.
* **Best for:** General use, covering a variety of topics related to effectiveness duration.

**Option 2: Focused on Timeframes**

> 了解不同情況下的持續時間、有效期、更新頻率等，所有關於「多久有效」的資訊都彙集於此。

* **Translation:** Understand durations, validity periods, update frequencies, etc. – all information about “How long it’s valid” is gathered here.
* **Best for:** Emphasizing time-related details and validity specifics.

**Option 3: Slightly More Elaborate**

> 想知道某項產品或服務可以用多久嗎？ 或是資訊的有效期限是多久？ 這個標籤將提供關於「多久有效」的解答，幫助您掌握資訊的時效性。

* **Translation:** Want to know how long a certain product or service lasts? Or how long is the validity period of information? This tag will provide answers regarding “How long it’s valid,” helping you stay informed about the timeliness of information.
* **Best for:** More informative and user-friendly.

**Additional Considerations:**

* **Target Audience:** Consider who your readers are. Choose the description that best clarifies the tag’s purpose to them.
* **Content of Posts:** Make sure the description accurately reflects the content you’ll tag with “多久有效.”
* **SEO:** Keep in mind some basic SEO principles. If you’re aiming for search engine visibility, consider keywords related to validity, expiration dates, and timeframes.

Choose the option that best suits your needs! You can easily adjust the phrasing to sound more natural and specific to your content. Remember to paste the description directly into the “Description” field when setting up the tag in your WordPress admin panel.