Exclude BaseModel docstring from JSON schema description (#8352)

pydantic/_internal/_generate_schema.py

@@ -212,6 +212,8 @@ def modify_model_json_schema(
     Returns:
         JsonSchemaValue: The updated JSON schema.
     """
+    from ..main import BaseModel
+
     json_schema = handler(schema_or_field)
     original_schema = handler.resolve_ref_schema(json_schema)
     # Preserve the fact that definitions schemas should never have sibling keys:
@@ -221,7 +223,8 @@ def modify_model_json_schema(
         original_schema['allOf'] = [{'$ref': ref}]
     if 'title' not in original_schema:
         original_schema['title'] = cls.__name__
-    docstring = cls.__doc__
+    # BaseModel; don't use cls.__doc__ as it will contain the verbose class signature by default
+    docstring = None if cls is BaseModel else cls.__doc__
     if docstring and 'description' not in original_schema:
         original_schema['description'] = inspect.cleandoc(docstring)
     return json_schema

tests/test_json_schema.py

@@ -5812,3 +5812,10 @@ class OuterModel(pydantic.BaseModel):
 
     with pytest.raises(ValidationError):
         OuterModel(x=2, y=-1, z=-1)
+
+
+def test_description_not_included_for_basemodel() -> None:
+    class Model(BaseModel):
+        x: BaseModel
+
+    assert 'description' not in Model.model_json_schema()['$defs']['BaseModel']