This post is to capture our new rules on what to write questions, as proposed in Getting Writers out of its Rut.
There are several kinds of questions that can be characterized as "what to write" questions. Some of them are on topic for us, and some are not. This post describes each of the types and provides the rationale for why it is on topic or not.
"How do I express this idea?" questions: on topic
This is the change to our previous rules. Questions that describe an idea that you want to get across and ask for help in expressing it well are on topic. This includes questions like this one: In a formal syntax notation, how should I indicate many optional elements?. Finding the best way to express an idea is one of the most fundamental skills of writing and such answer are potentially useful to other people trying to express similar ideas, as well as illustrating general principles of good communication. A good "express this idea" question should describe the idea and identify the audience to whom that idea is to be communicated.
"What's the right word for X?" questions: off topic
Choosing a single word is more about definitions than it is about writing. The answer to an "express this idea" question is often to rewrite the entire sentence or paragraph. Writers work at the sentence level. Individual words are the business of lexicographers. Single word requests are on topic for English SE.
Idea generation questions: off topic
An idea generation question is one that ask us to help the author generate ideas to write about. It includes question like, "I have to write an essay on squirrels for class, what should I write about them?" and "My fantasy world is inhabited by giant mushrooms. How should they celebrate Christmas". These questions are off topic for us because they are not fundamentally about writing itself, and because they are not likely to be of interest to anyone else. Some of these questions may be on topic on Worldbuilding SE.
"Please rewrite this sentence for me": off topic
The distinction between this and the help me express an idea questions may be a little fuzzy, but basically an "express this idea" question will contain a description of the idea to be expressed. It may or may not contain the authors current idea of how to express that idea. A rewrite question, on the other hand, tend to just contain the sentence in question, with no background. Questions that ask for a rewrite without describing the subject matter or identifying the audience can only be addressed as proofreading questions, which are off topic.
"Please proofread this for me": off topic
Questions that are essentially asking for proofreading, for fixing grammar and spelling for instance, are off topic as they are not likely to be of use to anyone else.
"Please critique my work": off topic
Questions that ask us to critique a piece of writing remain off topic.