fix(mcp): hide user directory metadata from responses (#39576)

Co-authored-by: Elizabeth Thompson <eschutho@gmail.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit_tests/mcp_service/utils/test_permissions_utils.py

@@ -0,0 +1,73 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+"""Tests for MCP field-level permission helpers."""
+
+from unittest.mock import Mock
+
+from superset.mcp_service.utils.permissions_utils import (
+    apply_field_permissions_to_columns,
+    filter_sensitive_data,
+    get_allowed_fields,
+)
+
+
+def test_get_allowed_fields_always_denies_user_directory_fields():
+    user = Mock()
+    user.roles = []
+
+    allowed_fields = get_allowed_fields(
+        "dashboard",
+        user=user,
+        requested_fields=["id", "dashboard_title", "owners", "roles", "created_by"],
+    )
+
+    assert allowed_fields == {"id", "dashboard_title"}
+
+
+def test_filter_sensitive_data_strips_user_directory_fields_even_if_allowed():
+    data = {
+        "id": 1,
+        "dashboard_title": "Executive Dashboard",
+        "owners": [{"username": "admin"}],
+        "roles": [{"name": "Admin"}],
+        "created_by": "admin",
+    }
+
+    filtered = filter_sensitive_data(
+        data,
+        "dashboard",
+        allowed_fields=set(data),
+    )
+
+    assert filtered == {
+        "id": 1,
+        "dashboard_title": "Executive Dashboard",
+    }
+
+
+def test_apply_field_permissions_to_columns_omits_user_directory_fields():
+    user = Mock()
+    user.roles = []
+
+    columns = apply_field_permissions_to_columns(
+        ["id", "slice_name", "owners", "changed_by_fk"],
+        "chart",
+        user=user,
+    )
+
+    assert columns == ["id", "slice_name"]

tests/unit_tests/mcp_service/utils/test_token_utils.py

@@ -220,6 +220,8 @@ class TestGenerateSizeReductionSuggestions:
             token_limit=25000,
         )
         assert any("filter" in s.lower() for s in suggestions)
+        assert not any("owner" in s.lower() for s in suggestions)
+        assert any("non-user attributes" in s for s in suggestions)
 
     def test_tool_specific_suggestions_execute_sql(self) -> None:
         """Should provide SQL-specific suggestions for execute_sql."""