diff --git a/tests/e2e/llm_translation/test_bedrock_native_e2e.py b/tests/e2e/llm_translation/test_bedrock_native_e2e.py
index 425d8b9b74a..95720bcace2 100644
--- a/tests/e2e/llm_translation/test_bedrock_native_e2e.py
+++ b/tests/e2e/llm_translation/test_bedrock_native_e2e.py
@@ -210,8 +210,8 @@ class TestBedrockNative:
     def test_bedrock_json_schema_response_exposes_text_before_json_tool_call(
         self, proxy: ProxyClient, resources: ResourceManager, sdk: SdkClients
     ) -> None:
-        model = f"e2e-bedrock-json-mode-preamble-{unique_marker()}"
-        model_id = proxy.create_model(
+        model: Final = f"e2e-bedrock-json-mode-preamble-{unique_marker()}"
+        model_id: Final = proxy.create_model(
             model,
             LiteLLMParamsBody(
                 model=BEDROCK_JSON_SCHEMA_BACKEND,
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 1c748f0c83d..09933605ade 100644
--- a/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
+++ b/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
@@ -9756,6 +9756,14 @@ def test_json_mode_text_without_tool_call_is_unchanged():
     assert message.tool_calls is None
     assert "json_mode_preamble_text" not in (message.provider_specific_fields or {})
 
+    preamble: Final = "Let me answer the question. "
+    json_result: Final = _transform_json_mode_body(
+        {**body, "content": [{"type": "text", "text": preamble}, *body["content"]]}
+    )
+    json_message: Final = json_result.choices[0].message
+    assert json_message.content == '{"answer": "Hello"}'
+    assert json_message.provider_specific_fields["json_mode_preamble_text"] == preamble
+
 
 def test_json_mode_with_a_real_tool_keeps_mixed_response_behavior():
     preamble: Final = "I will look up the details. "
@@ -9778,6 +9786,13 @@ def test_json_mode_with_a_real_tool_keeps_mixed_response_behavior():
     assert message.tool_calls[0].function.arguments == '{"location": "San Francisco"}'
     assert "json_mode_preamble_text" not in (message.provider_specific_fields or {})
 
+    json_result: Final = _transform_json_mode_body(
+        {**body, "content": [{"type": "text", "text": preamble}, *body["content"]]}
+    )
+    json_message: Final = json_result.choices[0].message
+    assert json_message.content == '{"answer": "Hello"}'
+    assert json_message.provider_specific_fields["json_mode_preamble_text"] == preamble
+
 
 def test_non_dict_upstream_body_still_transforms_without_refusal_fields() -> None:
     result = AnthropicConfig().transform_parsed_response(
diff --git a/tests/unit/llms/bedrock/chat/test_converse_transformation.py b/tests/unit/llms/bedrock/chat/test_converse_transformation.py
index f89ca376e47..fcdddb6daac 100644
--- a/tests/unit/llms/bedrock/chat/test_converse_transformation.py
+++ b/tests/unit/llms/bedrock/chat/test_converse_transformation.py
@@ -6761,7 +6761,7 @@ def _transform_json_mode_content_blocks(content: list[dict[str, object]]) -> Mod
             return json.dumps(response_json)
 
     return AmazonConverseConfig()._transform_response(
-        model="bedrock/us.anthropic.claude-haiku-4-5-20251001-v1:0",
+        model="bedrock/us.anthropic.claude-haiku-5-5",
         response=MockResponse(),
         model_response=ModelResponse(),
         stream=False,
@@ -6795,7 +6795,7 @@ def test_bedrock_json_mode_preserves_nonblank_text_before_json_tool_call():
 
 
 def test_bedrock_json_mode_omits_whitespace_only_preamble():
-    result: Final = _transform_json_mode_content_blocks(
+    whitespace_result: Final = _transform_json_mode_content_blocks(
         [
             {"text": " \n\t"},
             {
@@ -6808,9 +6808,25 @@ def test_bedrock_json_mode_omits_whitespace_only_preamble():
         ]
     )
 
-    message: Final = result.choices[0].message
-    assert message.content == '{"answer": 42}'
-    assert "json_mode_preamble_text" not in (message.provider_specific_fields or {})
+    whitespace_message: Final = whitespace_result.choices[0].message
+    assert whitespace_message.content == '{"answer": 42}'
+    assert "json_mode_preamble_text" not in (whitespace_message.provider_specific_fields or {})
+
+    preamble: Final = "Here is the answer. "
+    nonblank_result: Final = _transform_json_mode_content_blocks(
+        [
+            {"text": preamble},
+            {
+                "toolUse": {
+                    "toolUseId": "tooluse_json_001",
+                    "name": "json_tool_call",
+                    "input": {"answer": 42},
+                }
+            },
+        ]
+    )
+    nonblank_message: Final = nonblank_result.choices[0].message
+    assert nonblank_message.provider_specific_fields["json_mode_preamble_text"] == preamble
 
 
 def test_bedrock_json_mode_preamble_preserves_reasoning_content_fields():