diff --git a/src/agents/run_internal/tool_execution.py b/src/agents/run_internal/tool_execution.py
index af257b165f..71598cffc6 100644
--- a/src/agents/run_internal/tool_execution.py
+++ b/src/agents/run_internal/tool_execution.py
@@ -11,6 +11,7 @@
 import functools
 import inspect
 import json
+import math
 from collections.abc import Awaitable, Callable, Mapping, Sequence
 from typing import TYPE_CHECKING, Any, Literal, TypeVar, cast
 
@@ -694,7 +695,12 @@ def coerce_shell_call(tool_call: Any) -> ShellCallData:
     max_length_value = get_mapping_or_attr(action_payload, "max_output_length")
     if max_length_value is None:
         max_length_value = get_mapping_or_attr(action_payload, "maxOutputLength")
-    max_output_length = int(max_length_value) if isinstance(max_length_value, int | float) else None
+    if isinstance(max_length_value, int):
+        max_output_length = max_length_value
+    elif isinstance(max_length_value, float):
+        max_output_length = int(max_length_value) if math.isfinite(max_length_value) else 0
+    else:
+        max_output_length = None
 
     action = ShellActionRequest(
         commands=commands,
diff --git a/tests/test_shell_call_serialization.py b/tests/test_shell_call_serialization.py
index 6737c99eef..b0afcd0c18 100644
--- a/tests/test_shell_call_serialization.py
+++ b/tests/test_shell_call_serialization.py
@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import math
+
 import pytest
 
 from agents.agent import Agent
@@ -23,6 +25,31 @@ def test_coerce_shell_call_reads_max_output_length() -> None:
     assert result.action.max_output_length == 512
 
 
+@pytest.mark.parametrize("max_output_length", [math.nan, math.inf, -math.inf])
+def test_coerce_shell_call_ignores_non_finite_max_output_length(
+    max_output_length: float,
+) -> None:
+    tool_call = {
+        "call_id": "shell-non-finite-length",
+        "action": {"commands": ["ls"], "max_output_length": max_output_length},
+    }
+
+    result = run_loop.coerce_shell_call(tool_call)
+
+    assert result.action.max_output_length == 0
+
+
+def test_coerce_shell_call_preserves_large_integer_max_output_length() -> None:
+    tool_call = {
+        "call_id": "shell-large-length",
+        "action": {"commands": ["ls"], "max_output_length": 10**400},
+    }
+
+    result = run_loop.coerce_shell_call(tool_call)
+
+    assert result.action.max_output_length == 10**400
+
+
 @pytest.mark.parametrize("timeout_key", ["timeout_ms", "timeoutMs", "timeout"])
 @pytest.mark.parametrize("timeout_value", [0, 0.0])
 def test_coerce_shell_call_treats_zero_timeout_as_unspecified(