chore: Add sample agent to test support of output_schema and tools at the same time for gemini model

PiperOrigin-RevId: 792694074

contributing/samples/output_schema_with_tools/README.md

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+# Output Schema with Tools Sample Agent
+
+This sample demonstrates how to use structured output (`output_schema`) alongside other tools in an ADK agent. Previously, this combination was not allowed, but now it's supported through a special processor that handles the interaction.
+
+## How it Works
+
+The agent combines:
+- **Tools**: `search_wikipedia` and `get_current_year` for gathering information
+- **Structured Output**: `PersonInfo` schema to ensure consistent response format
+
+When both `output_schema` and `tools` are specified:
+1. ADK automatically adds a special `set_model_response` tool
+2. The model can use the regular tools for information gathering
+3. For the final response, the model uses `set_model_response` with structured data
+4. ADK extracts and validates the structured response
+
+## Expected Response Format
+
+The agent will return information in this structured format for user query "Tell me about Albert Einstein":
+
+```json
+{
+  "name": "Albert Einstein",
+  "age": 76,
+  "occupation": "Theoretical Physicist",
+  "location": "Princeton, New Jersey, USA",
+  "biography": "German-born theoretical physicist who developed the theory of relativity..."
+}
+```
+
+## Key Features Demonstrated
+
+1. **Tool Usage**: Agent can search Wikipedia and get current year
+2. **Structured Output**: Response follows strict PersonInfo schema
+3. **Validation**: ADK validates the response matches the schema
+4. **Flexibility**: Works with any combination of tools and output schemas

contributing/samples/output_schema_with_tools/__init__.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from . import agent

contributing/samples/output_schema_with_tools/agent.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Sample agent demonstrating output_schema with tools feature.
+
+This agent shows how to use structured output (output_schema) alongside
+other tools. Previously, this combination was not allowed, but now it's
+supported through a workaround that uses a special set_model_response tool.
+"""
+
+from google.adk.agents import LlmAgent
+from pydantic import BaseModel
+from pydantic import Field
+import requests
+
+
+class PersonInfo(BaseModel):
+  """Structured information about a person."""
+
+  name: str = Field(description="The person's full name")
+  age: int = Field(description="The person's age in years")
+  occupation: str = Field(description="The person's job or profession")
+  location: str = Field(description="The city and country where they live")
+  biography: str = Field(description="A brief biography of the person")
+
+
+def search_wikipedia(query: str) -> str:
+  """Search Wikipedia for information about a topic.
+
+  Args:
+    query: The search query to look up on Wikipedia
+
+  Returns:
+    Summary of the Wikipedia article if found, or error message if not found
+  """
+  try:
+    # Use Wikipedia API to search for the article
+    search_url = (
+        "https://en.wikipedia.org/api/rest_v1/page/summary/"
+        + query.replace(" ", "_")
+    )
+    response = requests.get(search_url, timeout=10)
+
+    if response.status_code == 200:
+      data = response.json()
+      return (
+          f"Title: {data.get('title', 'N/A')}\n\nSummary:"
+          f" {data.get('extract', 'No summary available')}"
+      )
+    else:
+      return (
+          f"Wikipedia article not found for '{query}'. Status code:"
+          f" {response.status_code}"
+      )
+
+  except Exception as e:
+    return f"Error searching Wikipedia: {str(e)}"
+
+
+def get_current_year() -> str:
+  """Get the current year.
+
+  Returns:
+    The current year as a string
+  """
+  from datetime import datetime
+
+  return str(datetime.now().year)
+
+
+# Create the agent with both output_schema and tools
+root_agent = LlmAgent(
+    name="person_info_agent",
+    model="gemini-1.5-pro",
+    instruction="""
+You are a helpful assistant that gathers information about famous people.
+
+When asked about a person, you should:
+1. Use the search_wikipedia tool to find information about them
+2. Use the get_current_year tool if you need to calculate ages
+3. Compile the information into a structured response using the PersonInfo format
+
+Always use the set_model_response tool to provide your final answer in the required structured format.
+    """.strip(),
+    output_schema=PersonInfo,
+    tools=[
+        search_wikipedia,
+        get_current_year,
+    ],
+)