diff --git a/scripts/odysseus-mcp b/scripts/odysseus-mcp
index 377e598..0a6d58c 100755
--- a/scripts/odysseus-mcp
+++ b/scripts/odysseus-mcp
@@ -42,7 +42,7 @@ def _serialize(s: "McpServer", redact_env: bool = True) -> dict:
         env_obj = json.loads(s.env) if s.env else {}
     except json.JSONDecodeError:
         env_obj = {}
-    if redact_env and env_obj:
+    if redact_env and isinstance(env_obj, dict):
         env_obj = {k: ("***" if v else "") for k, v in env_obj.items()}
     return {
         "id": s.id,
diff --git a/tests/test_mcp_cli_env_serialize.py b/tests/test_mcp_cli_env_serialize.py
new file mode 100644
index 0000000..2919728
--- /dev/null
+++ b/tests/test_mcp_cli_env_serialize.py
@@ -0,0 +1,44 @@
+"""Regression: mcp CLI _serialize must not crash when env JSON is not an object.
+
+`env_obj = json.loads(s.env)` can yield a list (e.g. env stored as "[1,2]").
+`if redact_env and env_obj:` then called `env_obj.items()` -> AttributeError.
+Guard with isinstance(dict).
+"""
+import importlib.machinery
+import importlib.util
+import sys
+import types
+from types import SimpleNamespace
+from pathlib import Path
+from unittest.mock import MagicMock
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def _load(monkeypatch):
+    db = types.ModuleType("core.database")
+    db.SessionLocal = MagicMock()
+    db.McpServer = MagicMock()
+    monkeypatch.setitem(sys.modules, "core.database", db)
+    loader = importlib.machinery.SourceFileLoader("odysseus_mcp_cli", str(ROOT / "scripts" / "odysseus-mcp"))
+    spec = importlib.util.spec_from_loader(loader.name, loader)
+    m = importlib.util.module_from_spec(spec)
+    loader.exec_module(m)
+    return m
+
+
+def _srv(env):
+    return SimpleNamespace(id="s1", name="n", transport="stdio", command="c", args="[]",
+                           env=env, url=None, is_enabled=1, oauth_config=None, created_at=None)
+
+
+def test_serialize_handles_list_env(monkeypatch):
+    cli = _load(monkeypatch)
+    out = cli._serialize(_srv("[1, 2]"))  # JSON array, not object
+    assert out["id"] == "s1"
+
+
+def test_serialize_redacts_dict_env(monkeypatch):
+    cli = _load(monkeypatch)
+    out = cli._serialize(_srv('{"API_KEY": "secret"}'))
+    assert out["env"] == {"API_KEY": "***"}