Refactor agent tool inputs and background activity logging

app/agent/tools/impl/run_workflow.py

@@ -14,8 +14,6 @@ from app.log import logger
 class RunWorkflowInput(BaseModel):
     """执行工作流工具的输入参数模型"""
 
-    explanation: Optional[str] = Field(None,
-        description="Clear explanation of why this tool is being used in the current context",)
     workflow_id: int = Field(
         ..., description="Workflow ID (can be obtained from query_workflows tool)"
     )