fixup: address Copilot review comments

- Remove duplicate pragma: no cover from raise line in session.py
- Strip {e} from OAuth error messages to avoid leaking token data;
  the chained exception already carries full details for debugging

Author: kiankhooban

src/mcp/client/auth/utils.py

@@ -241,7 +241,7 @@ async def handle_registration_response(response: Response) -> OAuthClientInforma
         client_info = OAuthClientInformationFull.model_validate_json(content)
         return client_info
     except ValidationError as e:  # pragma: no cover
-        raise OAuthRegistrationError(f"Invalid registration response: {e}") from e
+        raise OAuthRegistrationError("Invalid registration response") from e
 
 
 def is_valid_client_metadata_url(url: str | None) -> bool:
@@ -334,4 +334,4 @@ async def handle_token_response_scopes(
         token_response = OAuthToken.model_validate_json(content)
         return token_response
     except ValidationError as e:  # pragma: no cover
-        raise OAuthTokenError(f"Invalid token response: {e}") from e
+        raise OAuthTokenError("Invalid token response") from e

src/mcp/client/session.py

@@ -318,7 +318,7 @@ async def _validate_tool_result(self, name: str, result: types.CallToolResult) -
             except ValidationError as e:
                 raise RuntimeError(f"Invalid structured content returned by tool {name}: {e}") from e
             except SchemaError as e:  # pragma: no cover
-                raise RuntimeError(f"Invalid schema for tool {name}: {e}") from e  # pragma: no cover
+                raise RuntimeError(f"Invalid schema for tool {name}: {e}") from e
 
     async def list_prompts(self, *, params: types.PaginatedRequestParams | None = None) -> types.ListPromptsResult:
         """Send a prompts/list request.