Only send tool choice to Bedrock Converse API for Anthropic and Nova models (#2819)

Author: DouweM

pydantic_ai_slim/pydantic_ai/providers/bedrock.py

@@ -35,11 +35,19 @@ class BedrockModelProfile(ModelProfile):
     ALL FIELDS MUST BE `bedrock_` PREFIXED SO YOU CAN MERGE THEM WITH OTHER MODELS.
     """
 
-    bedrock_supports_tool_choice: bool = True
+    bedrock_supports_tool_choice: bool = False
     bedrock_tool_result_format: Literal['text', 'json'] = 'text'
     bedrock_send_back_thinking_parts: bool = False
 
 
+def bedrock_amazon_model_profile(model_name: str) -> ModelProfile | None:
+    """Get the model profile for an Amazon model used via Bedrock."""
+    profile = amazon_model_profile(model_name)
+    if 'nova' in model_name:
+        return BedrockModelProfile(bedrock_supports_tool_choice=True).update(profile)
+    return profile
+
+
 class BedrockProvider(Provider[BaseClient]):
     """Provider for AWS Bedrock."""
 
@@ -58,13 +66,13 @@ def client(self) -> BaseClient:
     def model_profile(self, model_name: str) -> ModelProfile | None:
         provider_to_profile: dict[str, Callable[[str], ModelProfile | None]] = {
             'anthropic': lambda model_name: BedrockModelProfile(
-                bedrock_supports_tool_choice=False, bedrock_send_back_thinking_parts=True
+                bedrock_supports_tool_choice=True, bedrock_send_back_thinking_parts=True
             ).update(anthropic_model_profile(model_name)),
             'mistral': lambda model_name: BedrockModelProfile(bedrock_tool_result_format='json').update(
                 mistral_model_profile(model_name)
             ),
             'cohere': cohere_model_profile,
-            'amazon': amazon_model_profile,
+            'amazon': bedrock_amazon_model_profile,
             'meta': meta_model_profile,
             'deepseek': deepseek_model_profile,
         }

tests/models/test_bedrock.py

@@ -844,15 +844,15 @@ async def test_bedrock_mistral_tool_result_format(bedrock_provider: BedrockProvi
     )
 
 
-async def test_bedrock_anthropic_no_tool_choice(bedrock_provider: BedrockProvider):
+async def test_bedrock_no_tool_choice(bedrock_provider: BedrockProvider):
     my_tool = ToolDefinition(
         name='my_tool',
         description='This is my tool',
         parameters_json_schema={'type': 'object', 'title': 'Result', 'properties': {'spam': {'type': 'number'}}},
     )
     mrp = ModelRequestParameters(output_mode='tool', function_tools=[my_tool], allow_text_output=False, output_tools=[])
 
-    # Models other than Anthropic support tool_choice
+    # Amazon Nova supports tool_choice
     model = BedrockConverseModel('us.amazon.nova-micro-v1:0', provider=bedrock_provider)
     tool_config = model._map_tool_config(mrp)  # type: ignore[reportPrivateUsage]
 
@@ -873,10 +873,31 @@ async def test_bedrock_anthropic_no_tool_choice(bedrock_provider: BedrockProvide
         }
     )
 
-    # Anthropic models don't support tool_choice
+    # Anthropic supports tool_choice
     model = BedrockConverseModel('us.anthropic.claude-3-7-sonnet-20250219-v1:0', provider=bedrock_provider)
     tool_config = model._map_tool_config(mrp)  # type: ignore[reportPrivateUsage]
 
+    assert tool_config == snapshot(
+        {
+            'tools': [
+                {
+                    'toolSpec': {
+                        'name': 'my_tool',
+                        'description': 'This is my tool',
+                        'inputSchema': {
+                            'json': {'type': 'object', 'title': 'Result', 'properties': {'spam': {'type': 'number'}}}
+                        },
+                    }
+                }
+            ],
+            'toolChoice': {'any': {}},
+        }
+    )
+
+    # Other models don't support tool_choice
+    model = BedrockConverseModel('us.meta.llama4-maverick-17b-instruct-v1:0', provider=bedrock_provider)
+    tool_config = model._map_tool_config(mrp)  # type: ignore[reportPrivateUsage]
+
     assert tool_config == snapshot(
         {
             'tools': [

tests/providers/test_bedrock.py

@@ -58,12 +58,12 @@ def test_bedrock_provider_model_profile(env: TestEnv, mocker: MockerFixture):
     anthropic_profile = provider.model_profile('us.anthropic.claude-3-5-sonnet-20240620-v1:0')
     anthropic_model_profile_mock.assert_called_with('claude-3-5-sonnet-20240620')
     assert isinstance(anthropic_profile, BedrockModelProfile)
-    assert not anthropic_profile.bedrock_supports_tool_choice
+    assert anthropic_profile.bedrock_supports_tool_choice is True
 
     anthropic_profile = provider.model_profile('anthropic.claude-instant-v1')
     anthropic_model_profile_mock.assert_called_with('claude-instant')
     assert isinstance(anthropic_profile, BedrockModelProfile)
-    assert not anthropic_profile.bedrock_supports_tool_choice
+    assert anthropic_profile.bedrock_supports_tool_choice is True
 
     mistral_profile = provider.model_profile('mistral.mistral-large-2407-v1:0')
     mistral_model_profile_mock.assert_called_with('mistral-large-2407')
@@ -84,7 +84,13 @@ def test_bedrock_provider_model_profile(env: TestEnv, mocker: MockerFixture):
     assert deepseek_profile is not None
     assert deepseek_profile.ignore_streamed_leading_whitespace is True
 
-    amazon_profile = provider.model_profile('amazon.titan-text-express-v1')
+    amazon_profile = provider.model_profile('us.amazon.nova-pro-v1:0')
+    amazon_model_profile_mock.assert_called_with('nova-pro')
+    assert isinstance(amazon_profile, BedrockModelProfile)
+    assert amazon_profile.json_schema_transformer == InlineDefsJsonSchemaTransformer
+    assert amazon_profile.bedrock_supports_tool_choice is True
+
+    amazon_profile = provider.model_profile('us.amazon.titan-text-express-v1:0')
     amazon_model_profile_mock.assert_called_with('titan-text-express')
     assert amazon_profile is not None
     assert amazon_profile.json_schema_transformer == InlineDefsJsonSchemaTransformer