Fix loading streaming Bedrock response with tool usage with empty argument

python/packages/autogen-ext/src/autogen_ext/models/anthropic/_anthropic_client.py

@@ -881,7 +881,8 @@ async def create_stream(
                     tool_calls[current_tool_id] = {
                         "id": chunk.content_block.id,
                         "name": chunk.content_block.name,
-                        "input": "",  # Will be populated from deltas
+                        "input": json.dumps(chunk.content_block.input),
+                        "partial_json": "",  # May be populated from deltas
                     }
 
             elif chunk.type == "content_block_delta":
@@ -896,10 +897,15 @@ async def create_stream(
                 elif hasattr(chunk.delta, "type") and chunk.delta.type == "input_json_delta":
                     if current_tool_id is not None and hasattr(chunk.delta, "partial_json"):
                         # Accumulate partial JSON for the current tool
-                        tool_calls[current_tool_id]["input"] += chunk.delta.partial_json
+                        tool_calls[current_tool_id]["partial_json"] += chunk.delta.partial_json
 
             elif chunk.type == "content_block_stop":
                 # End of a content block (could be text or tool)
+                if current_tool_id is not None:
+                    # If there was partial JSON accumulated, use it as the input
+                    if len(tool_calls[current_tool_id]["partial_json"]) > 0:
+                        tool_calls[current_tool_id]["input"] = tool_calls[current_tool_id]["partial_json"]
+                    del tool_calls[current_tool_id]["partial_json"]
                 current_tool_id = None
 
             elif chunk.type == "message_delta":

python/packages/autogen-ext/tests/models/test_anthropic_model_client.py

@@ -1,4 +1,5 @@
 import asyncio
+import json
 import logging
 import os
 from typing import List, Sequence
@@ -20,6 +21,7 @@
 from autogen_ext.models.anthropic import (
     AnthropicBedrockChatCompletionClient,
     AnthropicChatCompletionClient,
+    BaseAnthropicChatCompletionClient,
     BedrockInfo,
 )
 
@@ -34,6 +36,11 @@ def _add_numbers(a: int, b: int) -> int:
     return a + b
 
 
+def _ask_for_input() -> str:
+    """Function that asks for user input. Used to test empty input handling, such as in `pass_to_user` tool."""
+    return "Further input from user"
+
+
 @pytest.mark.asyncio
 async def test_mock_tool_choice_specific_tool() -> None:
     """Test tool_choice parameter with a specific tool using mocks."""
@@ -999,3 +1006,104 @@ async def test_anthropic_tool_choice_none_value_with_actual_api() -> None:
 
     # Should get a text response, not tool calls
     assert isinstance(result.content, str)
+
+
+def get_client_or_skip(provider: str) -> BaseAnthropicChatCompletionClient:
+    if provider == "anthropic":
+        api_key = os.getenv("ANTHROPIC_API_KEY")
+        if not api_key:
+            pytest.skip("ANTHROPIC_API_KEY not found in environment variables")
+
+        return AnthropicChatCompletionClient(
+            model="claude-3-haiku-20240307",
+            api_key=api_key,
+        )
+    else:
+        access_key = os.getenv("AWS_ACCESS_KEY_ID")
+        secret_key = os.getenv("AWS_SECRET_ACCESS_KEY")
+        region = os.getenv("AWS_REGION")
+        if not access_key or not secret_key or not region:
+            pytest.skip("AWS credentials not found in environment variables")
+
+        model = os.getenv("ANTHROPIC_BEDROCK_MODEL", "us.anthropic.claude-3-haiku-20240307-v1:0")
+        return AnthropicBedrockChatCompletionClient(
+            model=model,
+            bedrock_info=BedrockInfo(
+                aws_access_key=access_key,
+                aws_secret_key=secret_key,
+                aws_region=region,
+                aws_session_token=os.getenv("AWS_SESSION_TOKEN", ""),
+            ),
+            model_info=ModelInfo(
+                vision=False, function_calling=True, json_output=False, family="unknown", structured_output=True
+            ),
+        )
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("provider", ["anthropic", "bedrock"])
+async def test_streaming_tool_usage_with_no_arguments(provider: str) -> None:
+    """
+    Test reading streaming tool usage response with no arguments.
+    In that case `input` in initial `tool_use` chunk is `{}` and subsequent `partial_json` chunks are empty.
+    """
+    client = get_client_or_skip(provider)
+
+    # Define tools
+    ask_for_input_tool = FunctionTool(
+        _ask_for_input, description="Ask user for more input", name="ask_for_input", strict=True
+    )
+
+    chunks: List[str | CreateResult] = []
+    async for chunk in client.create_stream(
+        messages=[
+            SystemMessage(content="When user intent is unclear, ask for more input"),
+            UserMessage(content="Erm...", source="user"),
+        ],
+        tools=[ask_for_input_tool],
+        tool_choice="required",
+    ):
+        chunks.append(chunk)
+
+    assert len(chunks) > 0
+    assert isinstance(chunks[-1], CreateResult)
+    result: CreateResult = chunks[-1]
+    assert len(result.content) == 1
+    content = result.content[-1]
+    assert isinstance(content, FunctionCall)
+    assert content.name == "ask_for_input"
+    assert json.loads(content.arguments) is not None
+
+
+@pytest.mark.parametrize("provider", ["anthropic", "bedrock"])
+@pytest.mark.asyncio
+async def test_streaming_tool_usage_with_arguments(provider: str) -> None:
+    """
+    Test reading streaming tool usage response with arguments.
+    In that case `input` in initial `tool_use` chunk is `{}` but subsequent `partial_json` chunks make up the actual
+    complete input value.
+    """
+    client = get_client_or_skip(provider)
+
+    # Define tools
+    add_numbers = FunctionTool(_add_numbers, description="Add two numbers together", name="add_numbers")
+
+    chunks: List[str | CreateResult] = []
+    async for chunk in client.create_stream(
+        messages=[
+            SystemMessage(content="Use the tools to evaluate calculations"),
+            UserMessage(content="2 + 2", source="user"),
+        ],
+        tools=[add_numbers],
+        tool_choice="required",
+    ):
+        chunks.append(chunk)
+
+    assert len(chunks) > 0
+    assert isinstance(chunks[-1], CreateResult)
+    result: CreateResult = chunks[-1]
+    assert len(result.content) == 1
+    content = result.content[-1]
+    assert isinstance(content, FunctionCall)
+    assert content.name == "add_numbers"
+    assert json.loads(content.arguments) is not None