Python: Fix Gemini client support for Gemini API and Vertex AI (#5258)

* Add Gemini and Vertex AI client support

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address Gemini PR review feedback

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* removed sample run readme part

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Evan Mattson <35585003+moonbox3@users.noreply.github.com>

python/packages/core/agent_framework/_tools.py

@@ -906,6 +906,9 @@ def _tools_to_dict(  # pyright: ignore[reportUnusedFunction]
         if isinstance(tool_item, FunctionTool):
             results.append(tool_item.to_json_schema_spec())
             continue
+        if isinstance(tool_item, BaseModel):
+            results.append(tool_item.model_dump(exclude_none=True))
+            continue
         if isinstance(tool_item, SerializationMixin):
             results.append(tool_item.to_dict())
             continue

python/packages/core/tests/core/test_tools.py

@@ -16,12 +16,26 @@ from agent_framework._middleware import FunctionInvocationContext
 from agent_framework._tools import (
     _parse_annotation,
     _parse_inputs,
+    _tools_to_dict,
 )
 from agent_framework.observability import OtelAttr
 
 # region FunctionTool and tool decorator tests
 
 
+def test_tools_to_dict_supports_pydantic_tool_models() -> None:
+    """Pydantic-based tool specs are serialized without logging parse warnings."""
+
+    class ProviderTool(BaseModel):
+        kind: str
+        enabled: bool = True
+        note: str | None = None
+
+    result = _tools_to_dict([ProviderTool(kind="google_search")])
+
+    assert result == [{"kind": "google_search", "enabled": True}]
+
+
 def test_tool_decorator():
     """Test the tool decorator."""