Agent not effective

I referred to the example:

`

options = ClaudeAgentOptions(
agents={
"code-reviewer": AgentDefinition(
description="Reviews code for best practices and potential issues",
prompt="You are a code reviewer. Analyze code for bugs, performance issues, "
"security vulnerabilities, and adherence to best practices. "
"Provide constructive feedback.",
tools=["Read", "Grep"],
model="sonnet",
),
},
)

async for message in query(
prompt="Use the code-reviewer agent to review the code in src/claude_agent_sdk/types.py",
options=options,
):
if isinstance(message, AssistantMessage):
for block in message.content:
if isinstance(block, TextBlock):
print(f"Claude: {block.text}")
elif isinstance(message, ResultMessage) and message.total_cost_usd and message.total_cost_usd > 0:
print(f"\nCost: ${message.total_cost_usd:.4f}")
print()

`

Hello, when using multi-agent, I found that the returned content always uses Opus instead of Sonnet. Are there any relevant logs or other configurations I can check to troubleshoot the cause?