Tool annotations

from typing import Annotated, Literal

from pydantic import BaseModel, Field

from mcp.server import MCPServer
from mcp.server.mcpserver.exceptions import ToolError
from mcp.types import ToolAnnotations

mcp = MCPServer("Shop support")

ORDERS = {
    "A17": {"item": "blue mug", "status": "shipped", "total": 12.50},
    "B42": {"item": "desk lamp", "status": "processing", "total": 48.00},
}

ARTICLES = {
    "Where is my order?": "orders",
    "Changing an order": "orders",
    "How refunds work": "refunds",
    "Refunds for damaged items": "refunds",
    "Resetting your password": "account",
}


class Order(BaseModel):
    id: str
    item: str
    status: Literal["processing", "shipped", "delivered"]
    total: float


@mcp.tool(annotations=ToolAnnotations(read_only_hint=True))
def lookup_order(order_id: str) -> Order:
    """Look up an order by its id."""
    if order_id not in ORDERS:
        raise ToolError(f"No order with id {order_id!r}. Order ids look like A17.")
    return Order(id=order_id, **ORDERS[order_id])


@mcp.tool()
def search_help(
    query: Annotated[str, Field(description="Words to look for in the help articles.")],
    topic: Literal["orders", "refunds", "account"] | None = None,
    limit: Annotated[int, Field(ge=1, le=5)] = 3,
) -> str:
    """Search the help centre and return matching article titles."""
    found = [title for title, t in ARTICLES.items() if query.lower() in title.lower() and topic in (None, t)]
    return "; ".join(found[:limit]) or "No articles found."


@mcp.tool(
    title="Refund an order",
    annotations=ToolAnnotations(read_only_hint=False, destructive_hint=False, idempotent_hint=False),
)
def refund_order(order_id: str, reason: str) -> str:
    """Refund the full total of an order to the customer's card."""
    if order_id not in ORDERS:
        raise ToolError(f"No order with id {order_id!r}.")
    return f"Refunded {ORDERS[order_id]['total']:.2f} for order {order_id}: {reason}."