diff --git a/src/app.rs b/src/app.rs
index 1747b16..12c8f06 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -190,6 +190,8 @@ pub struct App {
     rm: remote_ui::RemoteUi,
     /// Running as `anybot --serve` (no window; the phone is the screen).
     headless: bool,
+    /// Running `anybot --ask` (one message from the command line, for testing tool use).
+    asking: bool,
     /// The computer the person last typed to a bot on: an account computer's id, "" for this
     /// one, None when not known (the phone isn't a computer). It is "我的電腦" to the bots.
     typed_on: Option<String>,
@@ -306,6 +308,7 @@ impl App {
             msg_index: 0,
             rm: Default::default(),
             headless: false,
+            asking: false,
             typed_on: None,
             panel: None,
             popped: HashMap::new(),
@@ -917,8 +920,9 @@ impl App {
             v.push(t);
         };
         // A brain on a server works on the bots' own computer and the person's computers, never on
-        // the server itself (the person asked for it to be off the list).
-        if !self.headless {
+        // the server itself (the person asked for it to be off the list). `anybot --ask` with
+        // ANYBOT_ASK_HERE=1 offers this computer too, for trying screen steps on it.
+        if !self.headless || (self.asking && std::env::var_os("ANYBOT_ASK_HERE").is_some()) {
             add(&mut v, tools::Target { name: self.state.this_computer_name(), place: tools::Place::Local { workdir: tools::expand_home(if b.workdir.trim().is_empty() { "~" } else { b.workdir.trim() }) } });
         }
         for c in &self.state.remote_computers {
@@ -3696,6 +3700,7 @@ impl App {
     pub fn ask_cli(ctx: &egui::Context, text: &str) -> ! {
         let mut app = App::new(ctx, None);
         app.headless = true;
+        app.asking = true;
         let id = app.state.primary_bot;
         let start = app.state.bot(id).map(|b| b.messages.len()).unwrap_or(0);
         app.drafts.insert(id, text.to_string());
diff --git a/src/tools.rs b/src/tools.rs
index 91fcdff..0ed3b2f 100644
--- a/src/tools.rs
+++ b/src/tools.rs
@@ -732,7 +732,7 @@ pub fn sandbox_note(cmd: &str, out: &str) -> Option<&'static str> {
         });
     }
     if (out.contains("Trace/BPT trap") || out.contains("指令因為收到訊號而終止")) && cmd.contains(".app/Contents/MacOS/") {
-        return Some("（這個 App 的指令列在 AnyBot 的沙盒裡會當掉，不是 App 壞了。用它的完整路徑單獨執行（不要接 ;、|、&& 或其他指令），App Store 版的 App 就會在沙盒外跑；不行就改用畫面操作。）");
+        return Some("（這個 App 的指令列在 AnyBot 的沙盒裡會當掉，不是 App 壞了，也不是參數的問題。用它的完整路徑單獨執行：不要接 ;、|、&&，也不要用 >、< 把輸出存到檔案（要處理輸出就先單獨執行，再用下一條指令處理），App Store 版的 App 就會在沙盒外跑；不行就改用畫面操作。）");
     }
     None
 }