feat: add structured capability types

Replace generic capability dictionaries with structured types for prompts,
resources, tools, and roots. This improves type safety and makes capability
features like listChanged and subscribe more explicit in the protocol.

tests/server/test_session.py

@@ -2,13 +2,15 @@ import anyio
 import pytest
 
 from mcp_python.client.session import ClientSession
-from mcp_python.server import Server
+from mcp_python.server import NotificationOptions, Server
 from mcp_python.server.session import ServerSession
 from mcp_python.server.types import InitializationOptions
 from mcp_python.types import (
     ClientNotification,
     InitializedNotification,
     JSONRPCMessage,
+    PromptsCapability,
+    ResourcesCapability,
     ServerCapabilities,
 )
 
@@ -71,9 +73,11 @@ async def test_server_session_initialize():
 @pytest.mark.anyio
 async def test_server_capabilities():
     server = Server("test")
+    notification_options = NotificationOptions()
+    experimental_capabilities = {}
 
     # Initially no capabilities
-    caps = server.get_capabilities()
+    caps = server.get_capabilities(notification_options, experimental_capabilities)
     assert caps.prompts is None
     assert caps.resources is None
 
@@ -82,8 +86,8 @@ async def test_server_capabilities():
     async def list_prompts():
         return []
 
-    caps = server.get_capabilities()
-    assert caps.prompts == {}
+    caps = server.get_capabilities(notification_options, experimental_capabilities)
+    assert caps.prompts == PromptsCapability(listChanged=False)
     assert caps.resources is None
 
     # Add a resources handler
@@ -91,6 +95,6 @@ async def test_server_capabilities():
     async def list_resources():
         return []
 
-    caps = server.get_capabilities()
-    assert caps.prompts == {}
-    assert caps.resources == {}
+    caps = server.get_capabilities(notification_options, experimental_capabilities)
+    assert caps.prompts == PromptsCapability(listChanged=False)
+    assert caps.resources == ResourcesCapability(subscribe=False, listChanged=False)