Removes handling for custom and unknown notifications

Author: kylestratis

README.md

@@ -2160,8 +2160,6 @@ Servers may send notifications, which derive from the `ServerNotification` class
 1. For each notification type you want to support, write a callback function that follows implements the matching protocol, such as `ToolListChangedFnT` for the tool list changed notification.
 2. Pass that function to the appropriate parameter when instantiating your client, e.g. `tool_list_changed_callback` for the tool list changed notification. This will be called every time your client receives the matching notification.
 
-You can also use this pattern with the `UnknownNotificationFnT` protocol to handle notification types that aren't anticipated in the SDK or by your code. This would handle custom notification types from the server.
-
 <!-- snippet-source examples/snippets/clients/server_notification_client.py -->
 ```python
 # Snippets demonstrating handling known and custom server notifications
@@ -2170,7 +2168,6 @@ import asyncio
 
 from mcp import ClientSession, StdioServerParameters
 from mcp.client.stdio import stdio_client
-from mcp.types import ServerNotification
 
 # Create dummy server parameters for stdio connection
 server_params = StdioServerParameters(
@@ -2186,19 +2183,12 @@ async def custom_resource_list_changed_handler() -> None:
     print("RESOURCE LIST CHANGED")
 
 
-# Create a fallback handler for custom notifications we aren't aware of.
-async def fallback_notification_handler(notification: ServerNotification) -> None:
-    """Fallback handler for unknown notifications."""
-    print(f"UNKNOWN notification caught: {notification.root.method}")
-
-
 async def run():
     async with stdio_client(server_params) as (read, write):
         async with ClientSession(
             read,
             write,
             resource_list_changed_callback=custom_resource_list_changed_handler,
-            unknown_notification_callback=fallback_notification_handler,
         ) as session:
             # Initialize the connection
             await session.initialize()
@@ -2213,10 +2203,6 @@ if __name__ == "__main__":
 _Full example: [examples/snippets/clients/server_notification_client.py](https://github.com/modelcontextprotocol/python-sdk/blob/main/examples/snippets/clients/server_notification_client.py)_
 <!-- /snippet-source -->
 
-If your client expects to connect to a server that sends custom notifications, you can create your handler or handlers, then pass them in a dictionary where the key is the notification literal and the value is a reference to the handler function. This dictionary is then passed in to the `custom_notification_handlers` parameter of the `ClientSession` constructor.
-
-For a runnable example, see [examples/snippets/clients/custom_notifications_example.py](https://github.com/modelcontextprotocol/python-sdk/blob/main/examples/snippets/clients/custom_notifications_example.py).
-
 ### Client Display Utilities
 
 When building MCP clients, the SDK provides utilities to help display human-readable names for tools, resources, and prompts: