diff --git a/homeassistant/helpers/llm.py b/homeassistant/helpers/llm.py
index 5a39bfaa726..d1ce3047e78 100644
--- a/homeassistant/helpers/llm.py
+++ b/homeassistant/helpers/llm.py
@@ -250,7 +250,9 @@ class AssistAPI(API):
         prompt = [
             (
                 "Call the intent tools to control Home Assistant. "
-                "When controlling an area, prefer passing area name and domain."
+                "When controlling a device, prefer passing just its name and its domain "
+                "(what comes before the dot in its entity id). "
+                "When controlling an area, prefer passing just area name and a single domain."
             )
         ]
         area: ar.AreaEntry | None = None
diff --git a/tests/helpers/test_llm.py b/tests/helpers/test_llm.py
index a59b4767196..672b6a6642b 100644
--- a/tests/helpers/test_llm.py
+++ b/tests/helpers/test_llm.py
@@ -423,7 +423,9 @@ async def test_assist_api_prompt(
     )
     first_part_prompt = (
         "Call the intent tools to control Home Assistant. "
-        "When controlling an area, prefer passing area name and domain."
+        "When controlling a device, prefer passing just its name and its domain "
+        "(what comes before the dot in its entity id). "
+        "When controlling an area, prefer passing just area name and a single domain."
     )
     no_timer_prompt = "This device does not support timers."