I have read carefully Contributor's Guide to English Language Learners ([Giving your question a title]). Somebody says the following sentences:
1. Is this grammatically correct?
2. Is the language of the Notice grammatically correct or not?
3. Is it grammatically correct?
4. Is the sentence grammatically correct?
5. Is this grammatically correct to use if outside?
6. Is 'on how to use' grammatically correct?
7. Which of the sentences is grammatically correct?
8. Which of these sentences is grammatically correct?
9. Is this strange sentence grammatically correct?
10. Is this quoted sentence grammatically correct?
Only 2, 5 and 6 are descriptive. The others are non-descriptive. Why are 2, 5 and 6 descriptive? I do not understand this.
The sentences are examples of question titles posted by users in the past
If the title of an English language question resembles like the ones below:
- Is this [sentence] (it) grammatical?
• Is this [sentence] (it) grammatically correct?
• Is this (strange/quoted) sentence grammatically correct?
- Which of the/these sentences is grammatically correct?
It does not tell the reader what the problem is. It does not describe the problem, at all. It is only a request to proofread the excerpt or sentence(s) the authors may have written or read somewhere.
These types of titles do not give us any useful information. They could all be asking about the same sentence(s). None of these examples tell users what the specific English language problem is.
On the other hand,
- Is 'on how to use' grammatically correct?
tells us the question is about a specific phrase “on how to use”, it is also asking whether it is grammatically correct but at the very least we know what the phrase is in the title, it is therefore a descriptive title.
Examples 2 and 5 are only marginally better because we know that one author is asking about a notice, and another author is asking if something (what??) is grammatical when used outside. I wouldn't call either of them descriptive, they are still very vague (and confusing) but at least they provide a tiny bit more description.