feat: Clarify NYC-only dataset and add no results message

samples/agent/adk/restaurant_finder/a2ui_examples.py

@@ -183,4 +183,24 @@
   }} }}
 ]
 ---END CONFIRMATION_EXAMPLE---
+
+---BEGIN NO_RESULTS_EXAMPLE---
+[
+  {{ "beginRendering": {{ "surfaceId": "default", "root": "root-column", "styles": {{ "primaryColor": "#FF0000", "font": "Roboto" }} }} }},
+  {{ "surfaceUpdate": {{
+    "surfaceId": "default",
+    "components": [
+      {{ "id": "root-column", "component": {{ "Column": {{ "children": {{ "explicitList": ["title-heading"] }} }} }} }},
+      {{ "id": "title-heading", "component": {{ "Text": {{ "usageHint": "h1", "text": {{ "path": "title" }} }} }} }}
+    ]
+  }} }},
+  {{ "dataModelUpdate": {{
+    "surfaceId": "default",
+    "path": "/",
+    "contents": [
+      {{ "key": "title", "valueString": "Sorry, our current dataset only includes restaurants in New York City. No restaurants were found in the specified location." }}
+    ]
+  }} }}
+]
+---END NO_RESULTS_EXAMPLE---
 """

samples/agent/adk/restaurant_finder/agent.py

@@ -44,6 +44,7 @@
     1.  **For finding restaurants:**
         a. You MUST call the `get_restaurants` tool. Extract the cuisine, location, and a specific number (`count`) of restaurants from the user's query (e.g., for "top 5 chinese places", count is 5).
         b. After receiving the data, you MUST follow the instructions precisely to generate the final a2ui UI JSON, using the appropriate UI example from the `prompt_builder.py` based on the number of restaurants.
+        c. If the get_restaurants tool returns an empty list ([]), you MUST use the NO_RESULTS_EXAMPLE to inform the user that no restaurants were found.
 
     2.  **For booking a table (when you receive a query like 'USER_WANTS_TO_BOOK...'):**
         a. You MUST use the appropriate UI example from `prompt_builder.py` to generate the UI, populating the `dataModelUpdate.contents` with the details from the user's query.

samples/agent/adk/restaurant_finder/prompt_builder.py

@@ -817,6 +817,7 @@ def get_ui_prompt(base_url: str, examples: str) -> str:
     -   If the number of restaurants is more than 5, you MUST use the `TWO_COLUMN_LIST_EXAMPLE` template.
     -   If the query is to book a restaurant (e.g., "USER_WANTS_TO_BOOK..."), you MUST use the `BOOKING_FORM_EXAMPLE` template.
     -   If the query is a booking submission (e.g., "User submitted a booking..."), you MUST use the `CONFIRMATION_EXAMPLE` template.
+    -   If the `get_restaurants` tool returns an empty list ([]), you MUST use the `NO_RESULTS_EXAMPLE` template.
 
     {formatted_examples}