docs: Use a trimmed ADK AgentConfig schema in Agent Builder Assistant

This trimmed schema includes only the fields relevant to agent shells, tool wiring, and common generation parameters, improving efficiency and focus.

The default model for the assistant has also been updated to "gemini-2.5-pro"

Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 829513627

contributing/samples/adk_agent_builder_assistant/agent_builder_assistant.py

@@ -45,9 +45,28 @@ from .utils import load_agent_config_schema
 class AgentBuilderAssistant:
   """Agent Builder Assistant factory for creating configured instances."""
 
+  _CORE_SCHEMA_DEF_NAMES: tuple[str, ...] = (
+      "LlmAgentConfig",
+      "LoopAgentConfig",
+      "ParallelAgentConfig",
+      "SequentialAgentConfig",
+      "BaseAgentConfig",
+      "AgentRefConfig",
+      "CodeConfig",
+      "ArgumentConfig",
+      "ToolArgsConfig",
+      "google__adk__tools__tool_configs__ToolConfig",
+  )
+  _GEN_CONFIG_FIELDS: tuple[str, ...] = (
+      "temperature",
+      "topP",
+      "topK",
+      "maxOutputTokens",
+  )
+
   @staticmethod
   def create_agent(
-      model: Union[str, BaseLlm] = "gemini-2.5-flash",
+      model: Union[str, BaseLlm] = "gemini-2.5-pro",
       working_directory: Optional[str] = None,
   ) -> LlmAgent:
     """Create Agent Builder Assistant with embedded ADK AgentConfig schema.
@@ -127,11 +146,9 @@ class AgentBuilderAssistant:
   def _load_schema() -> str:
     """Load ADK AgentConfig.json schema content and format for YAML embedding."""
 
-    # CENTRALIZED ADK AGENTCONFIG SCHEMA LOADING: Use common utility function
-    # This avoids duplication across multiple files and provides consistent
-    # ADK AgentConfig schema loading with caching and error handling.
-    schema_dict = load_agent_config_schema()
-    return AgentBuilderAssistant._build_schema_reference(schema_dict)
+    schema_dict = load_agent_config_schema(raw_format=False)
+    subset = AgentBuilderAssistant._extract_core_schema(schema_dict)
+    return AgentBuilderAssistant._build_schema_reference(subset)
 
   @staticmethod
   def _build_schema_reference(schema: dict[str, Any]) -> str:
@@ -300,6 +317,38 @@ class AgentBuilderAssistant:
 
     return "```text\n" + "\n".join(lines) + "\n```"
 
+  @staticmethod
+  def _extract_core_schema(schema: dict[str, Any]) -> dict[str, Any]:
+    """Return only the schema nodes surfaced by the assistant."""
+
+    defs = schema.get("$defs", {})
+    filtered_defs: dict[str, Any] = {}
+    for key in AgentBuilderAssistant._CORE_SCHEMA_DEF_NAMES:
+      if key in defs:
+        filtered_defs[key] = defs[key]
+
+    gen_config = defs.get("GenerateContentConfig")
+    if gen_config:
+      properties = gen_config.get("properties", {})
+      filtered_defs["GenerateContentConfig"] = {
+          "title": gen_config.get("title", "GenerateContentConfig"),
+          "description": (
+              "Common LLM generation knobs exposed by the Agent Builder."
+          ),
+          "type": "object",
+          "additionalProperties": False,
+          "properties": {
+              key: properties[key]
+              for key in AgentBuilderAssistant._GEN_CONFIG_FIELDS
+              if key in properties
+          },
+      }
+
+    return {
+        "$defs": filtered_defs,
+        "properties": schema.get("properties", {}),
+    }
+
   @staticmethod
   def _load_instruction_with_schema(
       model: Union[str, BaseLlm],