fix: validate function tool concurrency type

src/agents/run_config.py

@@ -122,9 +122,12 @@ class ToolExecutionConfig:
     """
 
     def __post_init__(self) -> None:
-        if self.max_function_tool_concurrency is not None and (
-            self.max_function_tool_concurrency < 1
-        ):
+        value = self.max_function_tool_concurrency
+        if value is not None and (isinstance(value, bool) or not isinstance(value, int)):
+            raise TypeError(
+                "tool_execution.max_function_tool_concurrency must be a positive integer or None"
+            )
+        if value is not None and value < 1:
             raise ValueError("tool_execution.max_function_tool_concurrency must be at least 1")
         if not isinstance(self.pre_approval_tool_input_guardrails, bool):
             raise ValueError("tool_execution.pre_approval_tool_input_guardrails must be a bool")

tests/test_run_config.py

@@ -334,6 +334,17 @@ def test_tool_execution_config_rejects_invalid_function_tool_concurrency() -> No
         ToolExecutionConfig(max_function_tool_concurrency=0)
 
 
+@pytest.mark.parametrize("value", [True, 1.5])
+def test_tool_execution_config_rejects_non_integer_function_tool_concurrency(
+    value: object,
+) -> None:
+    with pytest.raises(
+        TypeError,
+        match="tool_execution.max_function_tool_concurrency must be a positive integer or None",
+    ):
+        ToolExecutionConfig(max_function_tool_concurrency=cast(Any, value))
+
+
 def test_tool_execution_config_is_public_from_agents_package() -> None:
     config = RunConfig(tool_execution=ToolExecutionConfig(max_function_tool_concurrency=2))