test: Add basic parallel tool calling test to send_message v2 for anthropic [LET-5362] (#5355)

Add basic parallel tool calling test to send_message v2 for anthropic

tests/integration_test_send_message_v2.py

@@ -99,6 +99,13 @@ USER_MESSAGE_ROLL_DICE: List[MessageCreate] = [
         otid=USER_MESSAGE_OTID,
     )
 ]
+USER_MESSAGE_PARALLEL_TOOL_CALL: List[MessageCreate] = [
+    MessageCreate(
+        role="user",
+        content=("This is an automated test message. Please call the roll_dice tool three times in parallel."),
+        otid=USER_MESSAGE_OTID,
+    )
+]
 
 
 def assert_greeting_response(
@@ -515,6 +522,73 @@ async def test_greeting(
     TESTED_LLM_CONFIGS,
     ids=[c.model for c in TESTED_LLM_CONFIGS],
 )
+@pytest.mark.asyncio(loop_scope="function")
+async def test_parallel_tool_call_anthropic_streaming(
+    disable_e2b_api_key: Any,
+    client: AsyncLetta,
+    agent_state: AgentState,
+    llm_config: LLMConfig,
+) -> None:
+    if llm_config.model_endpoint_type != "anthropic":
+        pytest.skip("Parallel tool calling test only applies to Anthropic models.")
+
+    agent_state = await client.agents.modify(agent_id=agent_state.id, llm_config=llm_config)
+
+    stream = client.agents.messages.create_stream(
+        agent_id=agent_state.id,
+        messages=USER_MESSAGE_PARALLEL_TOOL_CALL,
+        stream_tokens=True,
+        background=False,
+    )
+    messages = await accumulate_chunks(stream)
+    run_id = messages[0].run_id if messages else None
+
+    # validate parallel tool call behavior in preserved messages
+    preserved_messages = await client.agents.messages.list(agent_id=agent_state.id)
+
+    # find the tool call message in preserved messages
+    tool_call_msg = None
+    tool_return_msg = None
+    for msg in preserved_messages:
+        if isinstance(msg, ToolCallMessage):
+            tool_call_msg = msg
+        elif isinstance(msg, ToolReturnMessage):
+            tool_return_msg = msg
+
+    # assert parallel tool calls were made
+    assert tool_call_msg is not None, "ToolCallMessage not found in preserved messages"
+    assert hasattr(tool_call_msg, "tool_calls"), "tool_calls field not found in ToolCallMessage"
+    assert len(tool_call_msg.tool_calls) == 3, f"Expected 3 parallel tool calls, got {len(tool_call_msg.tool_calls)}"
+
+    # verify each tool call
+    for tc in tool_call_msg.tool_calls:
+        assert tc["name"] == "roll_dice"
+        assert tc["tool_call_id"].startswith("toolu_")
+        assert "num_sides" in tc["arguments"]
+
+    # assert tool returns match the tool calls
+    assert tool_return_msg is not None, "ToolReturnMessage not found in preserved messages"
+    assert hasattr(tool_return_msg, "tool_returns"), "tool_returns field not found in ToolReturnMessage"
+    assert len(tool_return_msg.tool_returns) == 3, f"Expected 3 tool returns, got {len(tool_return_msg.tool_returns)}"
+
+    # verify each tool return
+    tool_call_ids = {tc["tool_call_id"] for tc in tool_call_msg.tool_calls}
+    for tr in tool_return_msg.tool_returns:
+        assert tr["type"] == "tool"
+        assert tr["status"] == "success"
+        assert tr["tool_call_id"] in tool_call_ids, f"tool_call_id {tr['tool_call_id']} not found in tool calls"
+        assert int(tr["tool_return"]) >= 1 and int(tr["tool_return"]) <= 6
+
+    if run_id:
+        await wait_for_run_completion(client, run_id)
+
+
+@pytest.mark.parametrize(
+    "llm_config",
+    TESTED_LLM_CONFIGS,
+    ids=[c.model for c in TESTED_LLM_CONFIGS],
+)
+@pytest.mark.parametrize("send_type", ["step", "stream_steps", "stream_tokens", "stream_tokens_background", "async"])
 @pytest.mark.parametrize(
     ["send_type", "cancellation"],
     list(