fix: Address review comments

src/admin/debug/commands.rs

@@ -1246,7 +1246,7 @@ impl crate::Context<'_> {
 		let backoff_map = self.services.federation.remote_health();
 
 		if backoff_map.is_empty() {
-			return Err!("No servers in backoff.");
+			return self.write_str("No servers are currently in backoff.").await;
 		}
 
 		let stale_map = self.services.federation.stale_destinations();

src/admin/debug/mod.rs

@@ -250,6 +250,13 @@ pub enum DebugCommand {
 		page: Option<usize>,
 	},
 
+	/// Lists remote servers that are currently in a "backoff" state.
+	///
+	/// Servers in this list will not be contacted until the retry time elapses,
+	/// or they make contact first.
+	///
+	/// "Stale" indicates that routing information may be out of date, and the
+	/// remote will be re-resolved immediately before the next contact attempt.
 	ServersInBackoff {
 		#[arg(short, long, alias = "room")]
 		room_id: Option<OwnedRoomId>,