fix: forward base_url and api_key from LLM to instructor client

When using an OpenAI-compatible provider with a custom base_url (e.g.
vLLM, Ollama, or any self-hosted endpoint), the InternalInstructor was
silently discarding the base_url and sending structured output requests
to api.openai.com instead of the configured endpoint.

The fix adds a _get_llm_extra_kwargs() method that extracts base_url
and api_key from the LLM object and forwards them as kwargs to
instructor.from_provider(), which already supports these parameters.

Fixes #5204

Co-Authored-By: João <joao@crewai.com>

lib/crewai/src/crewai/utilities/internal_instructor.py

@@ -98,7 +98,31 @@ class InternalInstructor(Generic[T]):
         else:
             provider = "openai"  # Default fallback
 
-        return instructor.from_provider(f"{provider}/{model_string}")
+        extra_kwargs = self._get_llm_extra_kwargs()
+
+        return instructor.from_provider(
+            f"{provider}/{model_string}", **extra_kwargs
+        )
+
+    def _get_llm_extra_kwargs(self) -> dict[str, Any]:
+        """Extract extra keyword arguments from the LLM to pass to the instructor client.
+
+        Forwards provider-specific configuration such as ``base_url`` and
+        ``api_key`` so that the instructor client connects to the correct
+        endpoint rather than defaulting to the provider's public API.
+
+        Returns:
+            Dictionary of extra keyword arguments for ``instructor.from_provider``.
+        """
+        if isinstance(self.llm, str) or self.llm is None:
+            return {}
+
+        extra: dict[str, Any] = {}
+        for attr in ("base_url", "api_key"):
+            value = getattr(self.llm, attr, None)
+            if value is not None:
+                extra[attr] = value
+        return extra
 
     def _extract_provider(self) -> str:
         """Extract provider from LLM model name.

lib/crewai/tests/utilities/test_converter.py

@@ -952,3 +952,134 @@ def test_internal_instructor_real_unsupported_provider() -> None:
 
     # Verify it's a configuration error about unsupported provider
     assert "Unsupported provider" in str(exc_info.value) or "unsupported" in str(exc_info.value).lower()
+
+
+def test_internal_instructor_forwards_base_url_to_from_provider() -> None:
+    """Test that _create_instructor_client forwards base_url from LLM to instructor.from_provider.
+
+    Regression test for https://github.com/crewAIInc/crewAI/issues/5204
+    When using an OpenAI-compatible provider with a custom base_url (e.g. vLLM, Ollama),
+    the InternalInstructor must pass base_url through so that structured output requests
+    reach the correct endpoint instead of defaulting to api.openai.com.
+    """
+    from crewai.utilities.internal_instructor import InternalInstructor
+
+    mock_llm = Mock()
+    mock_llm.is_litellm = False
+    mock_llm.model = "my-local-model"
+    mock_llm.provider = "openai"
+    mock_llm.base_url = "http://localhost:8000/v1"
+    mock_llm.api_key = "sk-custom-key"
+
+    with patch("instructor.from_provider") as mock_from_provider:
+        mock_client = Mock()
+        mock_from_provider.return_value = mock_client
+
+        InternalInstructor(
+            content="Test content",
+            model=SimpleModel,
+            llm=mock_llm,
+        )
+
+        mock_from_provider.assert_called_once_with(
+            "openai/my-local-model",
+            base_url="http://localhost:8000/v1",
+            api_key="sk-custom-key",
+        )
+
+
+def test_internal_instructor_forwards_base_url_without_api_key() -> None:
+    """Test that base_url is forwarded even when api_key is not set."""
+    from crewai.utilities.internal_instructor import InternalInstructor
+
+    mock_llm = Mock()
+    mock_llm.is_litellm = False
+    mock_llm.model = "my-local-model"
+    mock_llm.provider = "openai"
+    mock_llm.base_url = "http://localhost:11434/v1"
+    mock_llm.api_key = None
+
+    with patch("instructor.from_provider") as mock_from_provider:
+        mock_client = Mock()
+        mock_from_provider.return_value = mock_client
+
+        InternalInstructor(
+            content="Test content",
+            model=SimpleModel,
+            llm=mock_llm,
+        )
+
+        mock_from_provider.assert_called_once_with(
+            "openai/my-local-model",
+            base_url="http://localhost:11434/v1",
+        )
+
+
+def test_internal_instructor_no_extra_kwargs_when_base_url_not_set() -> None:
+    """Test that no extra kwargs are passed when base_url and api_key are not set."""
+    from crewai.utilities.internal_instructor import InternalInstructor
+
+    mock_llm = Mock()
+    mock_llm.is_litellm = False
+    mock_llm.model = "gpt-4o"
+    mock_llm.provider = "openai"
+    mock_llm.base_url = None
+    mock_llm.api_key = None
+
+    with patch("instructor.from_provider") as mock_from_provider:
+        mock_client = Mock()
+        mock_from_provider.return_value = mock_client
+
+        InternalInstructor(
+            content="Test content",
+            model=SimpleModel,
+            llm=mock_llm,
+        )
+
+        mock_from_provider.assert_called_once_with(
+            "openai/gpt-4o",
+        )
+
+
+def test_internal_instructor_get_llm_extra_kwargs_with_string_llm() -> None:
+    """Test that _get_llm_extra_kwargs returns empty dict for string LLM."""
+    from crewai.utilities.internal_instructor import InternalInstructor
+
+    with patch("instructor.from_provider") as mock_from_provider:
+        mock_client = Mock()
+        mock_from_provider.return_value = mock_client
+
+        inst = InternalInstructor(
+            content="Test content",
+            model=SimpleModel,
+            llm="openai/gpt-4o",
+        )
+
+        assert inst._get_llm_extra_kwargs() == {}
+
+
+def test_internal_instructor_forwards_only_api_key() -> None:
+    """Test that only api_key is forwarded when base_url is not set."""
+    from crewai.utilities.internal_instructor import InternalInstructor
+
+    mock_llm = Mock()
+    mock_llm.is_litellm = False
+    mock_llm.model = "gpt-4o"
+    mock_llm.provider = "openai"
+    mock_llm.base_url = None
+    mock_llm.api_key = "sk-my-key"
+
+    with patch("instructor.from_provider") as mock_from_provider:
+        mock_client = Mock()
+        mock_from_provider.return_value = mock_client
+
+        InternalInstructor(
+            content="Test content",
+            model=SimpleModel,
+            llm=mock_llm,
+        )
+
+        mock_from_provider.assert_called_once_with(
+            "openai/gpt-4o",
+            api_key="sk-my-key",
+        )