diff --git a/src/devx/tools/check_test_isolation.py b/src/devx/tools/check_test_isolation.py
index 7c9c207..8a9abbd 100644
--- a/src/devx/tools/check_test_isolation.py
+++ b/src/devx/tools/check_test_isolation.py
@@ -67,6 +67,8 @@ KNOWN_IO_FUNCTIONS: dict[str, str] = {  # nosec B105 — descriptions, not passw
     "get_pat": "reads ZITADEL PAT from filesystem/env (ZitadelAuth._iter_sources)",
     "load_secrets": "reads YAML config file from disk",
     "get_customer_secret": "reads customer-specific config from disk",
+    "get_customer_vm_ip": "queries Hetzner Cloud API for VM IP (network I/O)",
+    "get_observability_vm_ip": "queries Hetzner Cloud API for observability VM IP (network I/O)",
     "requests.get": "performs HTTP GET to a real server",
     "requests.post": "performs HTTP POST to a real server",
     "requests.put": "performs HTTP PUT to a real server",