diff --git a/common/birdxplorer_common/models.py b/common/birdxplorer_common/models.py
index 0e9801f..2a81b67 100644
--- a/common/birdxplorer_common/models.py
+++ b/common/birdxplorer_common/models.py
@@ -21,12 +21,14 @@
 from pydantic import Field as PydanticField
 from pydantic import (
     GetCoreSchemaHandler,
+    GetJsonSchemaHandler,
     HttpUrl,
     TypeAdapter,
     computed_field,
     model_validator,
 )
 from pydantic.alias_generators import to_camel
+from pydantic.json_schema import JsonSchemaValue
 from pydantic.main import IncEx
 from pydantic_core import core_schema
 
@@ -741,11 +743,30 @@ def from_url(cls, url: HttpUrl) -> "LinkId":
 
     @classmethod
     def __get_pydantic_core_schema__(cls, _source_type: Any, _handler: GetCoreSchemaHandler) -> core_schema.CoreSchema:
-        return core_schema.no_info_plain_validator_function(
-            cls.validate,
-            serialization=core_schema.plain_serializer_function_ser_schema(cls.serialize, when_used="json"),
+        return core_schema.union_schema(
+            [
+                core_schema.is_instance_schema(cls),
+                core_schema.no_info_plain_validator_function(cls.validate),
+            ],
+            serialization=core_schema.plain_serializer_function_ser_schema(
+                cls.serialize, info_arg=False, when_used="json"
+            ),
         )
 
+    @classmethod
+    def __get_pydantic_json_schema__(
+        cls, core_schema: core_schema.CoreSchema, handler: GetJsonSchemaHandler
+    ) -> JsonSchemaValue:
+        json_schema = handler(core_schema)
+        json_schema = handler.resolve_ref_schema(json_schema)
+        # __get_pydantic_core_schema__ に is_instance_schema を追加したが、
+        # APIから返却する際の実態は string (uuid) のみである
+        # この差分により、openapi specを自動生成する際に不要な anyOf: [] が生成されてしまうのを抑制する
+        del json_schema["anyOf"]
+        json_schema["type"] = "string"
+        json_schema["format"] = "uuid"
+        return json_schema
+
     @classmethod
     def validate(cls, v: Any) -> "LinkId":
         return cls(v)