From 6809224df9396eee7b78c26e83ae9baa74fdf68c Mon Sep 17 00:00:00 2001
From: mateo-berri <277851410+mateo-berri@users.noreply.github.com>
Date: Sat, 7 Nov 2026 00:50:21 -0800
Subject: [PATCH] fix(anthropic): type the decoded JSON mode answer as object
 and test non-object answers

json.loads output now goes through the existing TypeAdapter(object), which returns it unchanged, so no Any reaches the object guard. New stream and non-stream cases check that a list, string or number answer comes back as written.
---
 litellm/llms/base_llm/base_utils.py           |  4 +++-
 .../chat/test_anthropic_chat_handler.py       |  3 +++
 .../test_anthropic_chat_transformation.py     | 20 ++++++++++++++++++-
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/litellm/llms/base_llm/base_utils.py b/litellm/llms/base_llm/base_utils.py
index c4e077817f5..45f623730a8 100644
--- a/litellm/llms/base_llm/base_utils.py
+++ b/litellm/llms/base_llm/base_utils.py
@@ -239,7 +239,9 @@ def _is_decoded_json_object(
 
 def decoded_answer_object(text: str) -> Mapping[str, AnswerValue] | None:
     try:
-        decoded: Final[object] = json.loads(text, parse_float=_source_float, parse_int=_source_int)
+        decoded: Final = _DECODED_JSON.validate_python(
+            json.loads(text, parse_float=_source_float, parse_int=_source_int)
+        )
     except (json.JSONDecodeError, RecursionError):
         return None
     return decoded if _is_decoded_json_object(decoded) else None
diff --git a/tests/unit/llms/anthropic/chat/test_anthropic_chat_handler.py b/tests/unit/llms/anthropic/chat/test_anthropic_chat_handler.py
index 56a2f461bb4..c11fd58f84e 100644
--- a/tests/unit/llms/anthropic/chat/test_anthropic_chat_handler.py
+++ b/tests/unit/llms/anthropic/chat/test_anthropic_chat_handler.py
@@ -3262,6 +3262,9 @@ _DIGITS_PAST_THE_INT_LIMIT: Final = "1" * (sys.get_int_max_str_digits() + 1)
         (('{"n": 1e5}',), '{"n": 1e5}'),
         (('{"values": false}',), "false"),
         (('{"values": null}',), '{"values": null}'),
+        (("[1, 2]",), "[1, 2]"),
+        (('"x"',), '"x"'),
+        (("5",), "5"),
         pytest.param(
             ('{"values": ' + "[" * 300 + "]" * 300 + "}",),
             "[" * 300 + "]" * 300,
diff --git a/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py b/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
index d61384e8be5..bf093f1a0d8 100644
--- a/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
+++ b/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
@@ -8584,6 +8584,24 @@ def test_convert_tool_response_to_message_keeps_arguments_too_deep_to_decode(arg
     assert message.content == arguments
 
 
+@pytest.mark.parametrize("arguments", ["[1, 2]", '"x"', "5"])
+def test_convert_tool_response_to_message_keeps_a_non_object_answer_as_written(arguments: str) -> None:
+    message: Final = AnthropicConfig.convert_tool_response_to_message(
+        tool_calls=[
+            ChatCompletionToolCallChunk(
+                id="toolu_1",
+                type="function",
+                function=ChatCompletionToolCallFunctionChunk(name=RESPONSE_FORMAT_TOOL_NAME, arguments=arguments),
+                index=0,
+            )
+        ],
+        response_format_schema=None,
+    )
+
+    assert message is not None
+    assert message.content == arguments
+
+
 _DEEPLY_NESTED: Final = "[" * 300 + "]" * 300
 
 
@@ -8601,7 +8619,7 @@ _DEEPLY_NESTED: Final = "[" * 300 + "]" * 300
 )
 def test_convert_tool_response_to_message_unwraps_a_deeply_nested_answer(
     arguments: str, schema: dict[str, object] | None, expected: str
-):
+) -> None:
     message = AnthropicConfig.convert_tool_response_to_message(
         tool_calls=[
             ChatCompletionToolCallChunk(