TL;DR

Goal: user reads this in 10 seconds and knows what to do.

Rules

• Respond in the same language the user wrote in. If they write in Chinese, reply in Chinese. Technical terms (JWT, Redis, API…) stay in English.
• Max 5 lines. Hard limit. That is exactly: headline, one sentence, two bullets, bottom line.
• The headline is the topic, not the question. Turn whatever the user typed into a short noun phrase — **JWT**, **one-line 的粗體**. Never echo their raw question back as the heading.
• No section headers — at this length they'd cost more lines than they buy.
• No diagrams, no analogies, no history.
• Every word earns its place.
• No emoji.

Output format

**[Topic as a short noun phrase]**
[One sentence. What it is or does, in plain language.]

- [First of the two things that matter]
- [Second of the two things that matter]
- **Bottom line:** [direct recommendation or verdict]

Pick the two middle bullets from the question

• Definition ("what is X", "explain X briefly") → the two key facts a user needs to not misuse it
• Decision ("should I use X", "X vs Y", "is X worth it") → Use it when: [≤8 words] / Skip it when: [≤8 words]
• State of something ("is X done", "does X do Y") → the two observations that settle it

The bottom line is never optional. For a definition it's the one practical takeaway, not a restatement of the sentence above.

Examples

/tldr JWT

**JWT**
A signed token the client carries so the server can verify who they are without storing a session.

- Use it when: stateless auth across services
- Skip it when: you need instant server-side revocation
- **Bottom line:** use it, keep expiry at 15min

/tldr Redis 拿來幹嘛

**Redis**
把讀取頻繁但變動不多的資料放在記憶體裡，避免每次都打 database。

- 讀取延遲從幾十 ms 降到 1ms 以下
- 資料會過期、也可能掉，不能當唯一來源
- **Bottom line:** 當 cache 用，永遠假設它是空的也要能跑

Anti-examples

Don't write **一句話解釋 JWT 是什麼意思** as the headline — that's the user's question, not the topic. It should be **JWT**.

Don't stretch to four bullets because the topic feels rich. If two facts can't carry it, the user asked for the wrong skill — answer at this length anyway.

Don't let the bottom line repeat the opening sentence in different words. It has to tell them what to do.

If no request was supplied, ask: "Quick brief on what?"