diff --git a/python/cocoindex/tests/test_typing.py b/python/cocoindex/tests/test_typing.py
index aca08765..e786b96d 100644
--- a/python/cocoindex/tests/test_typing.py
+++ b/python/cocoindex/tests/test_typing.py
@@ -32,6 +32,14 @@ class SimpleDataclass:
     value: int
 
 
+@dataclasses.dataclass
+class SimpleDataclassWithDescription:
+    """This is a simple dataclass with a description."""
+
+    name: str
+    value: int
+
+
 class SimpleNamedTuple(NamedTuple):
     name: str
     value: int
@@ -357,45 +365,96 @@ def test_encode_enriched_type_none() -> None:
     assert result is None
 
 
-def test_encode_enriched_type_struct() -> None:
+def test_encode_enriched_dataclass() -> None:
     typ = SimpleDataclass
     result = encode_enriched_type(typ)
-    assert result["type"]["kind"] == "Struct"
-    assert len(result["type"]["fields"]) == 2
-    assert result["type"]["fields"][0]["name"] == "name"
-    assert result["type"]["fields"][0]["type"]["kind"] == "Str"
-    assert result["type"]["fields"][1]["name"] == "value"
-    assert result["type"]["fields"][1]["type"]["kind"] == "Int64"
+    assert result == {
+        "type": {
+            "kind": "Struct",
+            "description": "SimpleDataclass(name: str, value: int)",
+            "fields": [
+                {"name": "name", "type": {"kind": "Str"}},
+                {"name": "value", "type": {"kind": "Int64"}},
+            ],
+        },
+    }
+
+
+def test_encode_enriched_dataclass_with_description() -> None:
+    typ = SimpleDataclassWithDescription
+    result = encode_enriched_type(typ)
+    assert result == {
+        "type": {
+            "kind": "Struct",
+            "description": "This is a simple dataclass with a description.",
+            "fields": [
+                {"name": "name", "type": {"kind": "Str"}},
+                {"name": "value", "type": {"kind": "Int64"}},
+            ],
+        },
+    }
+
+
+def test_encode_named_tuple() -> None:
+    typ = SimpleNamedTuple
+    result = encode_enriched_type(typ)
+    assert result == {
+        "type": {
+            "kind": "Struct",
+            "description": "SimpleNamedTuple(name, value)",
+            "fields": [
+                {"name": "name", "type": {"kind": "Str"}},
+                {"name": "value", "type": {"kind": "Int64"}},
+            ],
+        },
+    }
 
 
 def test_encode_enriched_type_vector() -> None:
     typ = NDArray[np.float32]
     result = encode_enriched_type(typ)
-    assert result["type"]["kind"] == "Vector"
-    assert result["type"]["element_type"]["kind"] == "Float32"
-    assert result["type"]["dimension"] is None
+    assert result == {
+        "type": {
+            "kind": "Vector",
+            "element_type": {"kind": "Float32"},
+            "dimension": None,
+        },
+    }
 
 
 def test_encode_enriched_type_ltable() -> None:
     typ = list[SimpleDataclass]
     result = encode_enriched_type(typ)
-    assert result["type"]["kind"] == "LTable"
-    assert "fields" in result["type"]["row"]
-    assert len(result["type"]["row"]["fields"]) == 2
+    assert result == {
+        "type": {
+            "kind": "LTable",
+            "row": {
+                "description": "SimpleDataclass(name: str, value: int)",
+                "fields": [
+                    {"name": "name", "type": {"kind": "Str"}},
+                    {"name": "value", "type": {"kind": "Int64"}},
+                ],
+            },
+        },
+    }
 
 
 def test_encode_enriched_type_with_attrs() -> None:
     typ = Annotated[str, TypeAttr("key", "value")]
     result = encode_enriched_type(typ)
-    assert result["type"]["kind"] == "Str"
-    assert result["attrs"] == {"key": "value"}
+    assert result == {
+        "type": {"kind": "Str"},
+        "attrs": {"key": "value"},
+    }
 
 
 def test_encode_enriched_type_nullable() -> None:
     typ = str | None
     result = encode_enriched_type(typ)
-    assert result["type"]["kind"] == "Str"
-    assert result["nullable"] is True
+    assert result == {
+        "type": {"kind": "Str"},
+        "nullable": True,
+    }
 
 
 def test_encode_scalar_numpy_types_schema() -> None:
@@ -405,10 +464,9 @@ def test_encode_scalar_numpy_types_schema() -> None:
         (np.float64, "Float64"),
     ]:
         schema = encode_enriched_type(np_type)
-        assert schema["type"]["kind"] == expected_kind, (
-            f"Expected {expected_kind} for {np_type}, got {schema['type']['kind']}"
-        )
-        assert not schema.get("nullable", False)
+        assert schema == {
+            "type": {"kind": expected_kind},
+        }, f"Expected kind {expected_kind} for {np_type}, got {schema}"
 
 
 def test_annotated_struct_with_type_kind() -> None:
diff --git a/python/cocoindex/typing.py b/python/cocoindex/typing.py
index fea72571..35eaae19 100644
--- a/python/cocoindex/typing.py
+++ b/python/cocoindex/typing.py
@@ -444,7 +444,7 @@ def add_fields_from_struct(struct_info: AnalyzedStructType) -> None:
     add_fields_from_struct(struct_info)
 
     result["fields"] = fields
-    if doc := inspect.getdoc(struct_info):
+    if doc := inspect.getdoc(struct_info.struct_type):
         result["description"] = doc
     return result, num_key_parts