diff --git a/libs/partners/openai/langchain_openai/chat_models/base.py b/libs/partners/openai/langchain_openai/chat_models/base.py
index 901d0b09f3a3d..f9f6841aaf092 100644
--- a/libs/partners/openai/langchain_openai/chat_models/base.py
+++ b/libs/partners/openai/langchain_openai/chat_models/base.py
@@ -1140,11 +1140,13 @@ def with_structured_output(
                 The method for steering model generation, one of:
 
                     - "function_calling":
-                        Uses OpenAI's tool-calling (formerly called function calling) API:
-                        https://platform.openai.com/docs/guides/function-calling
+                        Uses OpenAI's tool-calling (formerly called function calling)
+                        API: https://platform.openai.com/docs/guides/function-calling
                     - "json_schema":
                         Uses OpenAI's Structured Output API:
-                        https://platform.openai.com/docs/guides/structured-outputs
+                        https://platform.openai.com/docs/guides/structured-outputs.
+                        Supported for "gpt-4o-mini", "gpt-4o-2024-08-06", and later
+                        models.
                     - "json_mode":
                         Uses OpenAI's JSON mode. Note that if using JSON mode then you
                         must include instructions for formatting the output into the
diff --git a/libs/partners/openai/tests/integration_tests/chat_models/test_base.py b/libs/partners/openai/tests/integration_tests/chat_models/test_base.py
index 1624363ed0e18..3e03755b765bd 100644
--- a/libs/partners/openai/tests/integration_tests/chat_models/test_base.py
+++ b/libs/partners/openai/tests/integration_tests/chat_models/test_base.py
@@ -1,7 +1,7 @@
 """Test ChatOpenAI chat model."""
 
 import base64
-from typing import Any, AsyncIterator, List, Optional, cast
+from typing import Any, AsyncIterator, List, Literal, Optional, cast
 
 import httpx
 import openai
@@ -796,13 +796,21 @@ class magic_function(BaseModel):
         next(model_with_invalid_tool_schema.stream(query))
 
 
-def test_structured_output_strict() -> None:
+@pytest.mark.parametrize(
+    ("model", "method", "strict"),
+    [("gpt-4o", "function_calling", True), ("gpt-4o-2024-08-06", "json_schema", None)],
+)
+def test_structured_output_strict(
+    model: str,
+    method: Literal["function_calling", "json_schema"],
+    strict: Optional[bool],
+) -> None:
     """Test to verify structured output with strict=True."""
 
     from pydantic import BaseModel as BaseModelProper
     from pydantic import Field as FieldProper
 
-    model = ChatOpenAI(model="gpt-4o", temperature=0)
+    llm = ChatOpenAI(model=model, temperature=0)
 
     class Joke(BaseModelProper):
         """Joke to tell user."""
@@ -814,7 +822,7 @@ class Joke(BaseModelProper):
     # Type ignoring since the interface only officially supports pydantic 1
     # or pydantic.v1.BaseModel but not pydantic.BaseModel from pydantic 2.
     # We'll need to do a pass updating the type signatures.
-    chat = model.with_structured_output(Joke, strict=True)  # type: ignore[arg-type]
+    chat = llm.with_structured_output(Joke, method=method, strict=strict)
     result = chat.invoke("Tell me a joke about cats.")
     assert isinstance(result, Joke)
 
@@ -822,7 +830,9 @@ class Joke(BaseModelProper):
         assert isinstance(chunk, Joke)
 
     # Schema
-    chat = model.with_structured_output(Joke.model_json_schema(), strict=True)
+    chat = llm.with_structured_output(
+        Joke.model_json_schema(), method=method, strict=strict
+    )
     result = chat.invoke("Tell me a joke about cats.")
     assert isinstance(result, dict)
     assert set(result.keys()) == {"setup", "punchline"}
@@ -831,3 +841,27 @@ class Joke(BaseModelProper):
         assert isinstance(chunk, dict)
     assert isinstance(chunk, dict)  # for mypy
     assert set(chunk.keys()) == {"setup", "punchline"}
+
+    # Invalid schema with optional fields:
+    class InvalidJoke(BaseModelProper):
+        """Joke to tell user."""
+
+        setup: str = FieldProper(description="question to set up a joke")
+        # Invalid field, can't have default value.
+        punchline: str = FieldProper(
+            default="foo", description="answer to resolve the joke"
+        )
+
+    chat = llm.with_structured_output(InvalidJoke, method=method, strict=strict)
+    with pytest.raises(openai.BadRequestError):
+        chat.invoke("Tell me a joke about cats.")
+    with pytest.raises(openai.BadRequestError):
+        next(chat.stream("Tell me a joke about cats."))
+
+    chat = llm.with_structured_output(
+        InvalidJoke.model_json_schema(), method=method, strict=strict
+    )
+    with pytest.raises(openai.BadRequestError):
+        chat.invoke("Tell me a joke about cats.")
+    with pytest.raises(openai.BadRequestError):
+        next(chat.stream("Tell me a joke about cats."))