from typing import Annotated

from pydantic import BaseModel, Field

from mcp.server import MCPServer

from mcp.server.mcpserver import Elicit, Resolve

mcp = MCPServer("Bookshop")

INVENTORY = {"Dune": 7, "Neuromancer": 0}

class Stock(BaseModel):

title: str

copies: int

class Backorder(BaseModel):

confirm: bool = Field(description="Order anyway and wait?")

async def check_stock(title: str) -> Stock:

return Stock(title=title, copies=INVENTORY.get(title, 0))

async def confirm_backorder(

title: str,

stock: Annotated[Stock, Resolve(check_stock)],

) -> Backorder | Elicit[Backorder]:

if stock.copies > 0:

return Backorder(confirm=True) # in stock: nothing to ask

return Elicit(f"{title!r} is out of stock (2-3 weeks). Order anyway?", Backorder)

@mcp.tool()

async def order_book(

title: str,

stock: Annotated[Stock, Resolve(check_stock)],

backorder: Annotated[Backorder, Resolve(confirm_backorder)],

) -> str:

"""Order a book from the shop."""

if not backorder.confirm:

return "No order placed."

if stock.copies == 0:

return f"Backordered {title!r}; it ships in 2-3 weeks."

return f"Ordered {title!r}."