diff --git a/util/opentelemetry-util-genai/src/opentelemetry/util/genai/types.py b/util/opentelemetry-util-genai/src/opentelemetry/util/genai/types.py
new file mode 100644
index 0000000000..44ce90ce5e
--- /dev/null
+++ b/util/opentelemetry-util-genai/src/opentelemetry/util/genai/types.py
@@ -0,0 +1,59 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed 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.
+
+
+from dataclasses import dataclass
+from typing import Any, Literal, Optional, Union
+
+
+@dataclass()
+class ToolCall:
+    type: Literal["tool_call"] = "tool_call"
+    arguments: Any
+    name: str
+    id: Optional[str]
+
+
+@dataclass()
+class ToolCallResponse:
+    type: Literal["tool_call_response"] = "tool_call_response"
+    response: Any
+    id: Optional[str]
+
+
+FinishReason = Literal[
+    "content_filter", "error", "length", "stop", "tool_calls"
+]
+
+
+@dataclass()
+class Text:
+    type: Literal["text"] = "text"
+    content: str
+
+
+MessagePart = Union[Text, ToolCall, ToolCallResponse, Any]
+
+
+@dataclass()
+class InputMessage:
+    role: str
+    parts: list[MessagePart]
+
+
+@dataclass()
+class OutputMessage:
+    role: str
+    parts: list[MessagePart]
+    finish_reason: Union[str, FinishReason]