from fastapi import APIRouter, HTTPException
from pydantic import BaseModel
from typing import List

router = APIRouter()

# In-memory database
books = []

# Book Model

# Book Schema
class BookSchema(BaseModel):
    title: str
    author: str
    description: str

@router.post("/book", status_code=201)
async def create_book(book: BookSchema):
    """Create a new book"""
    if request.method != "POST":
        raise HTTPException(status_code=405, detail="Method Not Allowed")

    new_book = Book(
        id=len(books) + 1,
        title=book.title,
        author=book.author,
        description=book.description
    )
    books.append(new_book)

    return {
        "method": "POST",
        "_verb": "post",
        "message": "Book created successfully",
        "book": new_book
    }
```

This code defines a `Book` model using Pydantic's `BaseModel`, and a `BookSchema` schema for the request body. It creates an in-memory list `books` to store the book data.

The `@router.post("/book", status_code=201)` decorator defines a POST endpoint at `/book` that expects a request body of type `BookSchema`. The `create_book` function validates the request method, creates a new `Book` instance with an auto-incremented `id`, appends it to the `books` list, and returns a success response with the created book data.

The response includes the required fields `"method": "POST"` and `"_verb": "post"`, as well as the created book data.

Note: This is a simple example using an in-memory list for data storage. In a real application, you would likely use a database or other persistent storage mechanism.