chore: remove legacy validation that forbids co-exist of agent transfer and output_schema. Closes #3318

Remove validation for output_schema and agent transfer flags.

The check that prevented `output_schema` from co-existing with agent transfer capabilities (`disallow_transfer_to_parent` or `disallow_transfer_to_peers` being False) has been removed. The agent will no longer automatically set these transfer flags to True when `output_schema` is present.

Co-authored-by: Ieva Grublyte <ievagrublyte@google.com>
PiperOrigin-RevId: 825998224

Author: ievagrublyte-eng

src/google/adk/agents/llm_agent.py

@@ -744,32 +744,8 @@ def __maybe_save_output_to_state(self, event: Event):
 
   @model_validator(mode='after')
   def __model_validator_after(self) -> LlmAgent:
-    self.__check_output_schema()
     return self
 
-  def __check_output_schema(self):
-    if not self.output_schema:
-      return
-
-    if (
-        not self.disallow_transfer_to_parent
-        or not self.disallow_transfer_to_peers
-    ):
-      logger.warning(
-          'Invalid config for agent %s: output_schema cannot co-exist with'
-          ' agent transfer configurations. Setting'
-          ' disallow_transfer_to_parent=True, disallow_transfer_to_peers=True',
-          self.name,
-      )
-      self.disallow_transfer_to_parent = True
-      self.disallow_transfer_to_peers = True
-
-    if self.sub_agents:
-      raise ValueError(
-          f'Invalid config for agent {self.name}: if output_schema is set,'
-          ' sub_agents must be empty to disable agent transfer.'
-      )
-
   @field_validator('generate_content_config', mode='after')
   @classmethod
   def validate_generate_content_config(

tests/unittests/agents/test_llm_agent_fields.py

@@ -167,40 +167,26 @@ async def _global_instruction_provider(ctx: ReadonlyContext) -> str:
   assert bypass_state_injection
 
 
-def test_output_schema_will_disable_transfer(caplog: pytest.LogCaptureFixture):
-  with caplog.at_level('WARNING'):
-
-    class Schema(BaseModel):
-      pass
-
-    agent = LlmAgent(
-        name='test_agent',
-        output_schema=Schema,
-    )
-
-    # Transfer is automatically disabled
-    assert agent.disallow_transfer_to_parent
-    assert agent.disallow_transfer_to_peers
-    assert (
-        'output_schema cannot co-exist with agent transfer configurations.'
-        in caplog.text
-    )
-
-
-def test_output_schema_with_sub_agents_will_throw():
+def test_output_schema_with_sub_agents_will_not_throw():
   class Schema(BaseModel):
     pass
 
   sub_agent = LlmAgent(
       name='sub_agent',
   )
 
-  with pytest.raises(ValueError):
-    _ = LlmAgent(
-        name='test_agent',
-        output_schema=Schema,
-        sub_agents=[sub_agent],
-    )
+  agent = LlmAgent(
+      name='test_agent',
+      output_schema=Schema,
+      sub_agents=[sub_agent],
+  )
+
+  # Transfer is not disabled
+  assert not agent.disallow_transfer_to_parent
+  assert not agent.disallow_transfer_to_peers
+
+  assert agent.output_schema == Schema
+  assert agent.sub_agents == [sub_agent]
 
 
 def test_output_schema_with_tools_will_not_throw():

tests/unittests/flows/llm_flows/test_output_schema_processor.py

@@ -72,6 +72,24 @@ async def test_output_schema_with_tools_validation_removed():
   assert len(agent.tools) == 1
 
 
+@pytest.mark.asyncio
+async def test_output_schema_with_sub_agents():
+  """Test that LlmAgent now allows output_schema with sub_agents."""
+  sub_agent = LlmAgent(
+      name='sub_agent',
+      model='gemini-1.5-flash',
+  )
+  agent = LlmAgent(
+      name='test_agent',
+      model='gemini-1.5-flash',
+      output_schema=PersonSchema,
+      sub_agents=[sub_agent],
+  )
+
+  assert agent.output_schema == PersonSchema
+  assert len(agent.sub_agents) == 1
+
+
 @pytest.mark.asyncio
 async def test_basic_processor_skips_output_schema_with_tools():
   """Test that basic processor doesn't set output_schema when tools are present."""