When I looked through the StackExchange documentation, I didn't find any documentation describing the fields. I have to study the request and response for a long time in order to understand why this or that field is needed. Is there user or official API documentation that I might be missing?
All I found is https://api.stackexchange.com/docs
The payload (both request and response) are described as Types.
You can switch the documentation page from category to type:
From there you find for example the Answer type
Note that the Green check mark means the field is part of the Default filter. Fields marked with a red-cross need to be added manually to a custom filter.
From the category view, the response and request objects are linked from the paragraph that explains the functionality of the end-point:
For the response types of the API it is important to understand the Wrapper that is a common across all responses, top level type that includes fields for errors, paging, backoff and the items collection itself.
If you use these types in a javascript/typescript setting with an IDE that has a language server, you might want to install the Stack Exchange API type declarations so you get intellisense/code-completion in your editing context.
