Allow non-file URI schemes for Root resources

Changed Root.uri from FileUrl to AnyUrl to support various URI schemes
(https://, git://, s3://, etc.) in addition to file:// URLs.

Author: Tapan Chugh

src/mcp/types.py

@@ -1,7 +1,7 @@
 from collections.abc import Callable
 from typing import Annotated, Any, Generic, Literal, TypeAlias, TypeVar
 
-from pydantic import BaseModel, ConfigDict, Field, FileUrl, RootModel
+from pydantic import BaseModel, ConfigDict, Field, RootModel
 from pydantic.networks import AnyUrl, UrlConstraints
 from typing_extensions import deprecated
 
@@ -1151,11 +1151,10 @@ class ListRootsRequest(Request[RequestParams | None, Literal["roots/list"]]):
 class Root(BaseModel):
     """Represents a root directory or file that the server can operate on."""
 
-    uri: FileUrl
+    uri: AnyUrl
     """
-    The URI identifying the root. This *must* start with file:// for now.
-    This restriction may be relaxed in future versions of the protocol to allow
-    other URI schemes.
+    The URI identifying the root. Can be any valid URI scheme (e.g., file://, https://,
+    git://, s3://, etc.). Servers should document which URI schemes they support.
     """
     name: str | None = None
     """

tests/client/test_list_roots_callback.py

@@ -1,5 +1,5 @@
 import pytest
-from pydantic import FileUrl
+from pydantic import AnyUrl
 
 from mcp.client.session import ClientSession
 from mcp.server.fastmcp.server import Context
@@ -20,11 +20,11 @@ async def test_list_roots_callback():
     callback_return = ListRootsResult(
         roots=[
             Root(
-                uri=FileUrl("file://users/fake/test"),
+                uri=AnyUrl("file://users/fake/test"),
                 name="Test Root 1",
             ),
             Root(
-                uri=FileUrl("file://users/fake/test/2"),
+                uri=AnyUrl("https://github.com/user/repo"),  # Non-file URL also works
                 name="Test Root 2",
             ),
         ]