diff --git a/tools/send_message_tool.py b/tools/send_message_tool.py
index b767cf66bb6..08fa20292e1 100644
--- a/tools/send_message_tool.py
+++ b/tools/send_message_tool.py
@@ -795,7 +795,7 @@ async def _send_telegram(token, chat_id, message, media_files=None, thread_id=No
     instead, bypassing MarkdownV2 conversion.
     """
     try:
-        from telegram import Bot
+        from telegram import Bot, MessageEntity
         from telegram.constants import ParseMode
 
         # Auto-detect HTML tags — if present, skip MarkdownV2 and send as HTML.
@@ -816,6 +816,14 @@ async def _send_telegram(token, chat_id, message, media_files=None, thread_id=No
                 formatted = message
             send_parse_mode = ParseMode.MARKDOWN_V2
 
+        # Detect @username patterns and create mention entities so
+        # require_mention on the receiving bot's Gateway can trigger.
+        _MENTION_RE = re.compile(r'@([a-zA-Z][a-zA-Z0-9_]{4,31})')
+        _entities = [
+            MessageEntity(type="mention", offset=m.start(), length=len(m.group()))
+            for m in _MENTION_RE.finditer(formatted)
+        ]
+
         # Honour a configured proxy (telegram.proxy_url in config.yaml, exported
         # as TELEGRAM_PROXY env var by load_gateway_config). Without this, the
         # standalone send path bypasses the proxy and times out in regions
@@ -876,7 +884,7 @@ async def _send_telegram(token, chat_id, message, media_files=None, thread_id=No
                 last_msg = await _send_telegram_message_with_retry(
                     bot,
                     chat_id=int_chat_id, text=formatted,
-                    parse_mode=send_parse_mode, **thread_kwargs
+                    parse_mode=send_parse_mode, entities=_entities, **thread_kwargs
                 )
             except Exception as md_error:
                 # Parse failed, fall back to plain text
@@ -897,7 +905,7 @@ async def _send_telegram(token, chat_id, message, media_files=None, thread_id=No
                     last_msg = await _send_telegram_message_with_retry(
                         bot,
                         chat_id=int_chat_id, text=plain,
-                        parse_mode=None, **thread_kwargs
+                        parse_mode=None, entities=_entities, **thread_kwargs
                     )
                 else:
                     raise