diff --git a/nanobot/agent/tools/mcp.py b/nanobot/agent/tools/mcp.py
index f5a41e10..28219892 100644
--- a/nanobot/agent/tools/mcp.py
+++ b/nanobot/agent/tools/mcp.py
@@ -174,7 +174,8 @@ def _redact_url(url: str) -> str:
     """
     try:
         parts = urllib.parse.urlsplit(url)
-        netloc = parts.hostname or ""
+        hostname = parts.hostname or ""
+        netloc = f"[{hostname}]" if ":" in hostname else hostname
         if parts.port:
             netloc = f"{netloc}:{parts.port}"
         return urllib.parse.urlunsplit((parts.scheme, netloc, parts.path, "", ""))
diff --git a/tests/tools/test_mcp_tool.py b/tests/tools/test_mcp_tool.py
index c2eb81e5..81676f18 100644
--- a/tests/tools/test_mcp_tool.py
+++ b/tests/tools/test_mcp_tool.py
@@ -1247,6 +1247,7 @@ async def test_connect_mcp_servers_enabled_tools_matches_sanitized_name(
     [
         ("https://user:secret@host.example/sse", "https://host.example/sse"),
         ("https://host.example:8443/mcp?token=abc#frag", "https://host.example:8443/mcp"),
+        ("https://user:secret@[::1]:8443/sse?token=abc", "https://[::1]:8443/sse"),
         ("https://host.example/sse", "https://host.example/sse"),
     ],
 )