Add description to intent handlers and use in LLM helper (#117864)

tests/helpers/test_llm.py

@@ -118,3 +118,21 @@ async def test_assist_api(hass: HomeAssistant) -> None:
         "response_type": "action_done",
         "speech": {},
     }
+
+
+async def test_assist_api_description(hass: HomeAssistant) -> None:
+    """Test intent description with Assist API."""
+
+    class MyIntentHandler(intent.IntentHandler):
+        intent_type = "test_intent"
+        description = "my intent handler"
+
+    intent.async_register(hass, MyIntentHandler())
+
+    assert len(llm.async_get_apis(hass)) == 1
+    api = llm.async_get_api(hass, "assist")
+    tools = api.async_get_tools()
+    assert len(tools) == 1
+    tool = tools[0]
+    assert tool.name == "test_intent"
+    assert tool.description == "my intent handler"