diff --git a/nimble/transport/emspi/src/ble_hci_emspi.c b/nimble/transport/emspi/src/ble_hci_emspi.c
index 96107855d..b5a5978cb 100644
--- a/nimble/transport/emspi/src/ble_hci_emspi.c
+++ b/nimble/transport/emspi/src/ble_hci_emspi.c
@@ -603,13 +603,7 @@ ble_hci_emspi_free_pkt(uint8_t type, uint8_t *cmdevt, struct os_mbuf *acl)
 }
 
 /**
- * Sends an HCI event from the controller to the host.
- *
- * @param cmd                   The HCI event to send.  This buffer must be
- *                                  allocated via ble_hci_trans_buf_alloc().
- *
- * @return                      0 on success;
- *                              A BLE_ERR_[...] error code on failure.
+ * Unsupported.  This is a host-only transport.
  */
 int
 ble_hci_trans_ll_evt_tx(uint8_t *cmd)
@@ -618,12 +612,7 @@ ble_hci_trans_ll_evt_tx(uint8_t *cmd)
 }
 
 /**
- * Sends ACL data from controller to host.
- *
- * @param om                    The ACL data packet to send.
- *
- * @return                      0 on success;
- *                              A BLE_ERR_[...] error code on failure.
+ * Unsupported.  This is a host-only transport.
  */
 int
 ble_hci_trans_ll_acl_tx(struct os_mbuf *om)
@@ -708,7 +697,7 @@ ble_hci_trans_cfg_ll(ble_hci_trans_rx_cmd_fn *cmd_cb,
                      ble_hci_trans_rx_acl_fn *acl_cb,
                      void *acl_arg)
 {
-    /* XXX: Unimplemented. */
+    /* Unsupported. */
     assert(0);
 }
 
diff --git a/nimble/transport/emspi/syscfg.yml b/nimble/transport/emspi/syscfg.yml
index c8c20980f..066deb7f1 100644
--- a/nimble/transport/emspi/syscfg.yml
+++ b/nimble/transport/emspi/syscfg.yml
@@ -20,13 +20,16 @@
 
 syscfg.defs:
     BLE_HCI_EMSPI:
-        description: 'Indicates that the emspi HCI transport is present.'
+        description: 'Indicates that the emspi host HCI transport is present.'
         value: 1
         restrictions:
             # XXX: This package only builds with the apollo2 MCU.
             # MCU-dependencies need to be removed.
             - MCU_APOLLO2
 
+            # This is a host-only transport.
+            - BLE_HOST
+
     BLE_HCI_EVT_HI_BUF_COUNT:
         description: 'Number of high-priority event buffers.'
         value:  2