FunctionTool partial support (#5183)

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## Why are these changes needed?

FunctionTool supports passing in a partial

## Related issue number

Closes #5151 

## Checks

- [x] I've included any doc changes needed for
https://microsoft.github.io/autogen/. See
https://microsoft.github.io/autogen/docs/Contribute#documentation to
build and test documentation locally.
- [x] I've added tests (if relevant) corresponding to the changes
introduced in this PR.
- [x] I've made sure all auto checks have passed.

python/packages/autogen-core/src/autogen_core/_function_utils.py

@@ -3,6 +3,7 @@
 
 import inspect
 import typing
+from functools import partial
 from logging import getLogger
 from typing import (
     Annotated,
@@ -41,7 +42,8 @@ def get_typed_signature(call: Callable[..., Any]) -> inspect.Signature:
     """
     signature = inspect.signature(call)
     globalns = getattr(call, "__globals__", {})
-    type_hints = typing.get_type_hints(call, globalns, include_extras=True)
+    func_call = call.func if isinstance(call, partial) else call
+    type_hints = typing.get_type_hints(func_call, globalns, include_extras=True)
     typed_params = [
         inspect.Parameter(
             name=param.name,

python/packages/autogen-core/src/autogen_core/tools/_function_tool.py

@@ -88,7 +88,7 @@ def __init__(
         self._func = func
         self._global_imports = global_imports
         signature = get_typed_signature(func)
-        func_name = name or func.__name__
+        func_name = name or func.func.__name__ if isinstance(func, functools.partial) else name or func.__name__
         args_model = args_base_model_from_signature(func_name + "args", signature)
         return_type = signature.return_annotation
         self._has_cancellation_support = "cancellation_token" in signature.parameters

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

@@ -1,4 +1,5 @@
 import inspect
+from functools import partial
 from typing import Annotated, List
 
 import pytest
@@ -109,6 +110,67 @@ def my_function(arg: str = "default") -> MyResult:
     assert "required" not in schema["parameters"]
 
 
+def test_func_tool_with_partial_positional_arguments_schema_generation() -> None:
+    """Test correct schema generation for a partial function with positional arguments."""
+
+    def get_weather(country: str, city: str) -> str:
+        return f"The temperature in {city}, {country} is 75°"
+
+    partial_function = partial(get_weather, "Germany")
+    tool = FunctionTool(partial_function, description="Partial function tool.")
+    schema = tool.schema
+
+    assert schema["name"] == "get_weather"
+    assert "description" in schema
+    assert schema["description"] == "Partial function tool."
+    assert "parameters" in schema
+    assert schema["parameters"]["type"] == "object"
+    assert schema["parameters"]["properties"].keys() == {"city"}
+    assert schema["parameters"]["properties"]["city"]["type"] == "string"
+    assert schema["parameters"]["properties"]["city"]["description"] == "city"
+    assert "required" in schema["parameters"]
+    assert schema["parameters"]["required"] == ["city"]
+    assert "country" not in schema["parameters"]["properties"]  # check country not in schema params
+    assert len(schema["parameters"]["properties"]) == 1
+
+
+def test_func_call_tool_with_kwargs_schema_generation() -> None:
+    """Test correct schema generation for a partial function with kwargs."""
+
+    def get_weather(country: str, city: str) -> str:
+        return f"The temperature in {city}, {country} is 75°"
+
+    partial_function = partial(get_weather, country="Germany")
+    tool = FunctionTool(partial_function, description="Partial function tool.")
+    schema = tool.schema
+
+    assert schema["name"] == "get_weather"
+    assert "description" in schema
+    assert schema["description"] == "Partial function tool."
+    assert "parameters" in schema
+    assert schema["parameters"]["type"] == "object"
+    assert schema["parameters"]["properties"].keys() == {"country", "city"}
+    assert schema["parameters"]["properties"]["city"]["type"] == "string"
+    assert schema["parameters"]["properties"]["country"]["type"] == "string"
+    assert "required" in schema["parameters"]
+    assert schema["parameters"]["required"] == ["city"]  # only city is required
+    assert len(schema["parameters"]["properties"]) == 2
+
+
+@pytest.mark.asyncio
+async def test_run_func_call_tool_with_kwargs_and_args() -> None:
+    """Test run partial function with kwargs and args."""
+
+    def get_weather(country: str, city: str, unit: str = "Celsius") -> str:
+        return f"The temperature in {city}, {country} is 75° {unit}"
+
+    partial_function = partial(get_weather, "Germany", unit="Fahrenheit")
+    tool = FunctionTool(partial_function, description="Partial function tool.")
+    result = await tool.run_json({"city": "Berlin"}, CancellationToken())
+    assert isinstance(result, str)
+    assert result == "The temperature in Berlin, Germany is 75° Fahrenheit"
+
+
 @pytest.mark.asyncio
 async def test_tool_run() -> None:
     tool = MyTool()