diff --git a/tools/send_message_tool.py b/tools/send_message_tool.py
index 391e03baa8..f99bcdaf46 100644
--- a/tools/send_message_tool.py
+++ b/tools/send_message_tool.py
@@ -248,6 +248,9 @@ def _parse_target_ref(platform_name: str, target_ref: str):
             return match.group(1), None, True
     if target_ref.lstrip("-").isdigit():
         return target_ref, None, True
+    # Matrix room IDs (start with !) and user IDs (start with @) are explicit
+    if platform_name == "matrix" and (target_ref.startswith("!") or target_ref.startswith("@")):
+        return target_ref, None, True
     return None, None, False