diff --git a/atvm/AGENTS.md b/atvm/AGENTS.md
index 0e89dd3..7acabaf 100644
--- a/atvm/AGENTS.md
+++ b/atvm/AGENTS.md
@@ -105,6 +105,7 @@ This file defines how to operate and maintain the ATVM workspace in `/home/aw/co
 - If any requested VM name is missing or not found, stop immediately and report the missing names; do not infer, substitute, or search for replacement VMs unless the operator explicitly requests a discovery/mapping step.
 - For `atvm_prep` requests, infer common option values from operator shorthand when intent is clear.
 - For any `atvm_prep` execution request, always present the exact planned `atvm_prep.py` command first and wait for explicit operator approval before running it.
+- Always execute `atvm_prep.py` on the ATVM Cypress controller host `192.168.3.190` (`atvm-cypres-vm-1`).
 - `atvm_prep` datastore shorthand mapping for `-n`:
   - `Gold` -> `AutomatedTest-VMBootImg-Gold`
   - `Gold2` -> `AutomatedTest-VMBootImg-Gold-2`
diff --git a/atvm/docs/automation/atvm-prep-reference.md b/atvm/docs/automation/atvm-prep-reference.md
index 41fc048..78ac09a 100644
--- a/atvm/docs/automation/atvm-prep-reference.md
+++ b/atvm/docs/automation/atvm-prep-reference.md
@@ -3,6 +3,7 @@
 This document summarizes the behavior of the controller-local prep script:
 - Host: `atvm-cypress-vm-1` (`192.168.3.190`)
 - Path: `/root/atvm_prep/atvm_prep.py`
+- Execution rule: run all `atvm_prep.py` commands on `192.168.3.190` (ATVM Cypress controller).
 
 Use this as a quick runbook when ATVM datastore/lun prep is requested.