From d752bafc6ae9e1436971baf6032e59575a3d0e56 Mon Sep 17 00:00:00 2001
From: Nilesh Patil <128893479+nileshpatil6@users.noreply.github.com>
Date: Sat, 16 May 2026 20:11:12 +0530
Subject: [PATCH] fix: support functools.partial objects as tools in t_tool()

Fixes #907

inspect.isfunction() returns False for functools.partial objects, so
passing a partial to tools= would silently fall through to the else
branch and return the partial object unchanged. The API then received
an invalid tool object and rejected it with 400 INVALID_ARGUMENT.

Add functools.partial to the callable check so partial functions get
wrapped in a FunctionDeclaration the same way regular functions do.
---
 google/genai/_transformers.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/google/genai/_transformers.py b/google/genai/_transformers.py
index c36524100..edc863602 100644
--- a/google/genai/_transformers.py
+++ b/google/genai/_transformers.py
@@ -18,6 +18,7 @@
 import base64
 from collections.abc import Iterable, Mapping
 from enum import Enum, EnumMeta
+from functools import partial as _partial
 import inspect
 import io
 import logging
@@ -959,7 +960,7 @@ def t_tool(
 ) -> Optional[Union[types.Tool, Any]]:
   if not origin:
     return None
-  if inspect.isfunction(origin) or inspect.ismethod(origin):
+  if inspect.isfunction(origin) or inspect.ismethod(origin) or isinstance(origin, _partial):
     return types.Tool(
         function_declarations=[
             types.FunctionDeclaration.from_callable(