diff --git a/nanobot/agent/loop.py b/nanobot/agent/loop.py
index 6ebebcd..d644845 100644
--- a/nanobot/agent/loop.py
+++ b/nanobot/agent/loop.py
@@ -163,13 +163,7 @@ class AgentLoop:
         """Remove <think>…</think> blocks that some models embed in content."""
         if not text:
             return None
-        # Remove complete think blocks (non-greedy)
-        cleaned = re.sub(r"<think>[\s\S]*?</think>", "", text)
-        # Remove any stray closing tags left without opening
-        cleaned = re.sub(r"</think>", "", cleaned)
-        # Remove any stray opening tag and everything after it (incomplete block)
-        cleaned = re.sub(r"<think>[\s\S]*$", "", cleaned)
-        return cleaned.strip() or None
+        return re.sub(r"<think>[\s\S]*?</think>", "", text).strip() or None
 
     @staticmethod
     def _tool_hint(tool_calls: list) -> str:
diff --git a/nanobot/channels/feishu.py b/nanobot/channels/feishu.py
index e3ab8a0..f657359 100644
--- a/nanobot/channels/feishu.py
+++ b/nanobot/channels/feishu.py
@@ -1137,6 +1137,52 @@ class FeishuChannel(BaseChannel):
         logger.debug("Bot entered p2p chat (user opened chat window)")
         pass
 
+    @staticmethod
+    def _format_tool_hint_lines(tool_hint: str) -> str:
+        """Split tool hints across lines on top-level call separators only."""
+        parts: list[str] = []
+        buf: list[str] = []
+        depth = 0
+        in_string = False
+        quote_char = ""
+        escaped = False
+
+        for i, ch in enumerate(tool_hint):
+            buf.append(ch)
+
+            if in_string:
+                if escaped:
+                    escaped = False
+                elif ch == "\\":
+                    escaped = True
+                elif ch == quote_char:
+                    in_string = False
+                continue
+
+            if ch in {'"', "'"}:
+                in_string = True
+                quote_char = ch
+                continue
+
+            if ch == "(":
+                depth += 1
+                continue
+
+            if ch == ")" and depth > 0:
+                depth -= 1
+                continue
+
+            if ch == "," and depth == 0:
+                next_char = tool_hint[i + 1] if i + 1 < len(tool_hint) else ""
+                if next_char == " ":
+                    parts.append("".join(buf).rstrip())
+                    buf = []
+
+        if buf:
+            parts.append("".join(buf).strip())
+
+        return "\n".join(part for part in parts if part)
+
     async def _send_tool_hint_card(self, receive_id_type: str, receive_id: str, tool_hint: str) -> None:
         """Send tool hint as an interactive card with formatted code block.
 
@@ -1147,9 +1193,8 @@ class FeishuChannel(BaseChannel):
         """
         loop = asyncio.get_running_loop()
 
-        # Format: put each tool call on its own line for readability
-        # _tool_hint joins multiple calls with ", "
-        formatted_code = tool_hint.replace(", ", ",\n") if ", " in tool_hint else tool_hint
+        # Put each top-level tool call on its own line without altering commas inside arguments.
+        formatted_code = self._format_tool_hint_lines(tool_hint)
 
         card = {
             "config": {"wide_screen_mode": True},
diff --git a/tests/test_feishu_tool_hint_code_block.py b/tests/test_feishu_tool_hint_code_block.py
index a3fc024..2a1b812 100644
--- a/tests/test_feishu_tool_hint_code_block.py
+++ b/tests/test_feishu_tool_hint_code_block.py
@@ -114,3 +114,25 @@ async def test_tool_hint_multiple_tools_in_one_message(mock_feishu_channel):
         # Each tool call should be on its own line
         expected_md = "**Tool Calls**\n\n```text\nweb_search(\"query\"),\nread_file(\"/path/to/file\")\n```"
         assert content["elements"][0]["content"] == expected_md
+
+
+@mark.asyncio
+async def test_tool_hint_keeps_commas_inside_arguments(mock_feishu_channel):
+    """Commas inside a single tool argument must not be split onto a new line."""
+    msg = OutboundMessage(
+        channel="feishu",
+        chat_id="oc_123456",
+        content='web_search("foo, bar"), read_file("/path/to/file")',
+        metadata={"_tool_hint": True}
+    )
+
+    with patch.object(mock_feishu_channel, '_send_message_sync') as mock_send:
+        await mock_feishu_channel.send(msg)
+
+        content = json.loads(mock_send.call_args[0][3])
+        expected_md = (
+            "**Tool Calls**\n\n```text\n"
+            "web_search(\"foo, bar\"),\n"
+            "read_file(\"/path/to/file\")\n```"
+        )
+        assert content["elements"][0]["content"] == expected_md