Constant LOOP_STOP_TOOL 

pub(crate) const LOOP_STOP_TOOL: &str = r#"{
  "name": "LoopStop",
  "description": "Stop a recurring loop started by Loop(). Pass the loop_id it returned. Loops also stop automatically when the agent pane closes or max_iterations is reached.",
  "inputSchema": {
    "type": "object",
    "properties": {
      "loop_id": { "type": "string", "description": "The loop_id returned by a prior Loop() call" }
    },
    "required": ["loop_id"]
  }
}"#;