Java Spring Boot OpenApi 3 - How to add description for RequestBody?

I want to have a description for RequestBody in spring boot openapi 3, so I make my code like this:

@PostMapping(produces = "application/json", consumes = "application/json")
public ResponseEntity<Book> addBook(
    @Schema(
            description = "Book to add.",
            required=true,
            schema=@Schema(implementation = Book.class))
    @Valid @RequestBody Book book
) {
    return ResponseEntity.ok(bookRepository.add(Book));
}

RequestBody description is Book to add. My desired UI is like this:

But nothing happens. There is no description in my UI.

description was added to Schemas panel Book entity !!!

What is the problem?

From your Code Snippet, it seems to me as if your description actually belongs into the @RequestBody Annotation instead of the @Schema Annotation.

With @Schema, you define and describe your Models, but what you actually want to do is to describe the parameter in the context of your operation.

Try something along the lines of:

@PostMapping(produces = "application/json", consumes = "application/json")
public ResponseEntity<Book> addBook(
    @RequestBody(description = "Book to add.", required = true,
                content = @Content(
                        schema=@Schema(implementation = Book.class)))   
    @Valid Book book
) {
    return ResponseEntity.ok(bookRepository.add(Book));
}