diff --git a/build_support/catalog/test_update.py b/build_support/catalog/test_update.py
index 1ee941b6c..b3abfa56b 100644
--- a/build_support/catalog/test_update.py
+++ b/build_support/catalog/test_update.py
@@ -821,3 +821,27 @@ def test_empty_catalog_produces_valid_am(self, tmp_path):
         update.update_makefile(catalog_dir=tmp_path, am_path=am)
         content = am.read_text()
         assert content.startswith("CATALOG_FILES =")
+
+
+@pytest.mark.catalog_update
+class TestWarnMissingDescriptions:
+    """Tests for ``_warn_missing_descriptions(df)``.
+
+    The function prints to stderr for each game in a supported format that has
+    an empty description.  Tests use ``capsys`` to capture stderr output.
+    """
+
+    def test_game_without_description_warns(self, capsys):
+        """A game with an empty description produces a WARNING on stderr."""
+        df = _make_df(_efg_row("journals/nobody2025/fig1", description=""))
+        update._warn_missing_descriptions(df)
+        err = capsys.readouterr().err
+        assert "WARNING" in err
+        assert "journals/nobody2025/fig1" in err
+
+    def test_game_with_description_does_not_warn(self, capsys):
+        """A game with a non-empty description produces no output."""
+        df = _make_df(_efg_row("journals/nobody2025/fig1"))
+        update._warn_missing_descriptions(df)
+        err = capsys.readouterr().err
+        assert err == ""
diff --git a/build_support/catalog/update.py b/build_support/catalog/update.py
index f61acc014..ccfb77634 100644
--- a/build_support/catalog/update.py
+++ b/build_support/catalog/update.py
@@ -1,5 +1,6 @@
 import argparse
 import shutil
+import sys
 from pathlib import Path
 
 import pandas as pd
@@ -93,6 +94,23 @@ def _node_label(prefix: str, labels: dict[str, str]) -> str:
     return Path(prefix).name.replace("_", " ").title()
 
 
+def _warn_missing_descriptions(df: pd.DataFrame) -> None:
+    """Print a warning to stderr for each game that lacks a description.
+
+    Games without descriptions are silently excluded from the catalog page by
+    ``_build_slug_tree``.  This function makes that visible so contributors
+    know to add a description before the game will appear.
+    """
+    for _, row in df.iterrows():
+        if str(row.get("Description", "")).strip():
+            continue
+        print(
+            f"WARNING: '{row['Game']}' has no description and will not appear in the catalog.\n"
+            f"Add a description to the game file to include it.",
+            file=sys.stderr,
+        )
+
+
 def _build_slug_tree(df: pd.DataFrame) -> dict:
     """Build a nested dict tree from the slugs in *df*.
 
@@ -392,6 +410,7 @@ def update_makefile(
 
     # Create RST list-table used by doc/catalog.rst
     df = gbt.catalog.games(include_descriptions=True)
+    _warn_missing_descriptions(df)
     generate_rst_table(df, CATALOG_RST_TABLE, regenerate_images=args.regenerate_images)
     print(f"Generated {CATALOG_RST_TABLE} for use in local docs build. DO NOT COMMIT.")
     if args.build: