Add is_enabled to handoffs (#925)

Was added to function tools before, now handoffs. Towards #918

Author: rm-openai

src/agents/handoffs.py

@@ -15,6 +15,7 @@
 from .strict_schema import ensure_strict_json_schema
 from .tracing.spans import SpanError
 from .util import _error_tracing, _json, _transforms
+from .util._types import MaybeAwaitable
 
 if TYPE_CHECKING:
     from .agent import Agent
@@ -99,6 +100,11 @@ class Handoff(Generic[TContext]):
     True, as it increases the likelihood of correct JSON input.
     """
 
+    is_enabled: bool | Callable[[RunContextWrapper[Any], Agent[Any]], MaybeAwaitable[bool]] = True
+    """Whether the handoff is enabled. Either a bool or a Callable that takes the run context and
+    agent and returns whether the handoff is enabled. You can use this to dynamically enable/disable
+    a handoff based on your context/state."""
+
     def get_transfer_message(self, agent: Agent[Any]) -> str:
         return json.dumps({"assistant": agent.name})
 
@@ -121,6 +127,7 @@ def handoff(
     tool_name_override: str | None = None,
     tool_description_override: str | None = None,
     input_filter: Callable[[HandoffInputData], HandoffInputData] | None = None,
+    is_enabled: bool | Callable[[RunContextWrapper[Any], Agent[Any]], MaybeAwaitable[bool]] = True,
 ) -> Handoff[TContext]: ...
 
 
@@ -133,6 +140,7 @@ def handoff(
     tool_description_override: str | None = None,
     tool_name_override: str | None = None,
     input_filter: Callable[[HandoffInputData], HandoffInputData] | None = None,
+    is_enabled: bool | Callable[[RunContextWrapper[Any], Agent[Any]], MaybeAwaitable[bool]] = True,
 ) -> Handoff[TContext]: ...
 
 
@@ -144,6 +152,7 @@ def handoff(
     tool_description_override: str | None = None,
     tool_name_override: str | None = None,
     input_filter: Callable[[HandoffInputData], HandoffInputData] | None = None,
+    is_enabled: bool | Callable[[RunContextWrapper[Any], Agent[Any]], MaybeAwaitable[bool]] = True,
 ) -> Handoff[TContext]: ...
 
 
@@ -154,6 +163,7 @@ def handoff(
     on_handoff: OnHandoffWithInput[THandoffInput] | OnHandoffWithoutInput | None = None,
     input_type: type[THandoffInput] | None = None,
     input_filter: Callable[[HandoffInputData], HandoffInputData] | None = None,
+    is_enabled: bool | Callable[[RunContextWrapper[Any], Agent[Any]], MaybeAwaitable[bool]] = True,
 ) -> Handoff[TContext]:
     """Create a handoff from an agent.
 
@@ -166,6 +176,9 @@ def handoff(
         input_type: the type of the input to the handoff. If provided, the input will be validated
             against this type. Only relevant if you pass a function that takes an input.
         input_filter: a function that filters the inputs that are passed to the next agent.
+        is_enabled: Whether the handoff is enabled. Can be a bool or a callable that takes the run
+            context and agent and returns whether the handoff is enabled. Disabled handoffs are
+            hidden from the LLM at runtime.
     """
     assert (on_handoff and input_type) or not (on_handoff and input_type), (
         "You must provide either both on_handoff and input_type, or neither"
@@ -233,4 +246,5 @@ async def _invoke_handoff(
         on_invoke_handoff=_invoke_handoff,
         input_filter=input_filter,
         agent_name=agent.name,
+        is_enabled=is_enabled,
     )

src/agents/run.py

@@ -2,6 +2,7 @@
 
 import asyncio
 import copy
+import inspect
 from dataclasses import dataclass, field
 from typing import Any, Generic, cast
 
@@ -361,7 +362,8 @@ async def run(
                     # agent changes, or if the agent loop ends.
                     if current_span is None:
                         handoff_names = [
-                            h.agent_name for h in AgentRunner._get_handoffs(current_agent)
+                            h.agent_name
+                            for h in await AgentRunner._get_handoffs(current_agent, context_wrapper)
                         ]
                         if output_schema := AgentRunner._get_output_schema(current_agent):
                             output_type_name = output_schema.name()
@@ -641,7 +643,10 @@ async def _start_streaming(
                 # Start an agent span if we don't have one. This span is ended if the current
                 # agent changes, or if the agent loop ends.
                 if current_span is None:
-                    handoff_names = [h.agent_name for h in cls._get_handoffs(current_agent)]
+                    handoff_names = [
+                        h.agent_name
+                        for h in await cls._get_handoffs(current_agent, context_wrapper)
+                    ]
                     if output_schema := cls._get_output_schema(current_agent):
                         output_type_name = output_schema.name()
                     else:
@@ -798,7 +803,7 @@ async def _run_single_turn_streamed(
             agent.get_prompt(context_wrapper),
         )
 
-        handoffs = cls._get_handoffs(agent)
+        handoffs = await cls._get_handoffs(agent, context_wrapper)
         model = cls._get_model(agent, run_config)
         model_settings = agent.model_settings.resolve(run_config.model_settings)
         model_settings = RunImpl.maybe_reset_tool_choice(agent, tool_use_tracker, model_settings)
@@ -898,7 +903,7 @@ async def _run_single_turn(
         )
 
         output_schema = cls._get_output_schema(agent)
-        handoffs = cls._get_handoffs(agent)
+        handoffs = await cls._get_handoffs(agent, context_wrapper)
         input = ItemHelpers.input_to_new_input_list(original_input)
         input.extend([generated_item.to_input_item() for generated_item in generated_items])
 
@@ -1091,14 +1096,28 @@ def _get_output_schema(cls, agent: Agent[Any]) -> AgentOutputSchemaBase | None:
         return AgentOutputSchema(agent.output_type)
 
     @classmethod
-    def _get_handoffs(cls, agent: Agent[Any]) -> list[Handoff]:
+    async def _get_handoffs(
+        cls, agent: Agent[Any], context_wrapper: RunContextWrapper[Any]
+    ) -> list[Handoff]:
         handoffs = []
         for handoff_item in agent.handoffs:
             if isinstance(handoff_item, Handoff):
                 handoffs.append(handoff_item)
             elif isinstance(handoff_item, Agent):
                 handoffs.append(handoff(handoff_item))
-        return handoffs
+
+        async def _check_handoff_enabled(handoff_obj: Handoff) -> bool:
+            attr = handoff_obj.is_enabled
+            if isinstance(attr, bool):
+                return attr
+            res = attr(context_wrapper, agent)
+            if inspect.isawaitable(res):
+                return bool(await res)
+            return bool(res)
+
+        results = await asyncio.gather(*(_check_handoff_enabled(h) for h in handoffs))
+        enabled: list[Handoff] = [h for h, ok in zip(handoffs, results) if ok]
+        return enabled
 
     @classmethod
     async def _get_all_tools(

tests/test_agent_config.py

@@ -43,7 +43,7 @@ async def test_handoff_with_agents():
         handoffs=[agent_1, agent_2],
     )
 
-    handoffs = AgentRunner._get_handoffs(agent_3)
+    handoffs = await AgentRunner._get_handoffs(agent_3, RunContextWrapper(None))
     assert len(handoffs) == 2
 
     assert handoffs[0].agent_name == "agent_1"
@@ -78,7 +78,7 @@ async def test_handoff_with_handoff_obj():
         ],
     )
 
-    handoffs = AgentRunner._get_handoffs(agent_3)
+    handoffs = await AgentRunner._get_handoffs(agent_3, RunContextWrapper(None))
     assert len(handoffs) == 2
 
     assert handoffs[0].agent_name == "agent_1"
@@ -112,7 +112,7 @@ async def test_handoff_with_handoff_obj_and_agent():
         handoffs=[handoff(agent_1), agent_2],
     )
 
-    handoffs = AgentRunner._get_handoffs(agent_3)
+    handoffs = await AgentRunner._get_handoffs(agent_3, RunContextWrapper(None))
     assert len(handoffs) == 2
 
     assert handoffs[0].agent_name == "agent_1"

tests/test_handoff_tool.py

@@ -38,24 +38,26 @@ def get_len(data: HandoffInputData) -> int:
     return input_len + pre_handoff_len + new_items_len
 
 
-def test_single_handoff_setup():
+@pytest.mark.asyncio
+async def test_single_handoff_setup():
     agent_1 = Agent(name="test_1")
     agent_2 = Agent(name="test_2", handoffs=[agent_1])
 
     assert not agent_1.handoffs
     assert agent_2.handoffs == [agent_1]
 
-    assert not AgentRunner._get_handoffs(agent_1)
+    assert not (await AgentRunner._get_handoffs(agent_1, RunContextWrapper(agent_1)))
 
-    handoff_objects = AgentRunner._get_handoffs(agent_2)
+    handoff_objects = await AgentRunner._get_handoffs(agent_2, RunContextWrapper(agent_2))
     assert len(handoff_objects) == 1
     obj = handoff_objects[0]
     assert obj.tool_name == Handoff.default_tool_name(agent_1)
     assert obj.tool_description == Handoff.default_tool_description(agent_1)
     assert obj.agent_name == agent_1.name
 
 
-def test_multiple_handoffs_setup():
+@pytest.mark.asyncio
+async def test_multiple_handoffs_setup():
     agent_1 = Agent(name="test_1")
     agent_2 = Agent(name="test_2")
     agent_3 = Agent(name="test_3", handoffs=[agent_1, agent_2])
@@ -64,7 +66,7 @@ def test_multiple_handoffs_setup():
     assert not agent_1.handoffs
     assert not agent_2.handoffs
 
-    handoff_objects = AgentRunner._get_handoffs(agent_3)
+    handoff_objects = await AgentRunner._get_handoffs(agent_3, RunContextWrapper(agent_3))
     assert len(handoff_objects) == 2
     assert handoff_objects[0].tool_name == Handoff.default_tool_name(agent_1)
     assert handoff_objects[1].tool_name == Handoff.default_tool_name(agent_2)
@@ -76,7 +78,8 @@ def test_multiple_handoffs_setup():
     assert handoff_objects[1].agent_name == agent_2.name
 
 
-def test_custom_handoff_setup():
+@pytest.mark.asyncio
+async def test_custom_handoff_setup():
     agent_1 = Agent(name="test_1")
     agent_2 = Agent(name="test_2")
     agent_3 = Agent(
@@ -95,7 +98,7 @@ def test_custom_handoff_setup():
     assert not agent_1.handoffs
     assert not agent_2.handoffs
 
-    handoff_objects = AgentRunner._get_handoffs(agent_3)
+    handoff_objects = await AgentRunner._get_handoffs(agent_3, RunContextWrapper(agent_3))
     assert len(handoff_objects) == 2
 
     first_handoff = handoff_objects[0]
@@ -284,3 +287,86 @@ def test_get_transfer_message_is_valid_json() -> None:
     obj = handoff(agent)
     transfer = obj.get_transfer_message(agent)
     assert json.loads(transfer) == {"assistant": agent.name}
+
+
+def test_handoff_is_enabled_bool():
+    """Test that handoff respects is_enabled boolean parameter."""
+    agent = Agent(name="test")
+
+    # Test enabled handoff (default)
+    handoff_enabled = handoff(agent)
+    assert handoff_enabled.is_enabled is True
+
+    # Test explicitly enabled handoff
+    handoff_explicit_enabled = handoff(agent, is_enabled=True)
+    assert handoff_explicit_enabled.is_enabled is True
+
+    # Test disabled handoff
+    handoff_disabled = handoff(agent, is_enabled=False)
+    assert handoff_disabled.is_enabled is False
+
+
+@pytest.mark.asyncio
+async def test_handoff_is_enabled_callable():
+    """Test that handoff respects is_enabled callable parameter."""
+    agent = Agent(name="test")
+
+    # Test callable that returns True
+    def always_enabled(ctx: RunContextWrapper[Any], agent: Agent[Any]) -> bool:
+        return True
+
+    handoff_callable_enabled = handoff(agent, is_enabled=always_enabled)
+    assert callable(handoff_callable_enabled.is_enabled)
+    result = handoff_callable_enabled.is_enabled(RunContextWrapper(agent), agent)
+    assert result is True
+
+    # Test callable that returns False
+    def always_disabled(ctx: RunContextWrapper[Any], agent: Agent[Any]) -> bool:
+        return False
+
+    handoff_callable_disabled = handoff(agent, is_enabled=always_disabled)
+    assert callable(handoff_callable_disabled.is_enabled)
+    result = handoff_callable_disabled.is_enabled(RunContextWrapper(agent), agent)
+    assert result is False
+
+    # Test async callable
+    async def async_enabled(ctx: RunContextWrapper[Any], agent: Agent[Any]) -> bool:
+        return True
+
+    handoff_async_enabled = handoff(agent, is_enabled=async_enabled)
+    assert callable(handoff_async_enabled.is_enabled)
+    result = await handoff_async_enabled.is_enabled(RunContextWrapper(agent), agent)  # type: ignore
+    assert result is True
+
+
+@pytest.mark.asyncio
+async def test_handoff_is_enabled_filtering_integration():
+    """Integration test that disabled handoffs are filtered out by the runner."""
+
+    # Set up agents
+    agent_1 = Agent(name="agent_1")
+    agent_2 = Agent(name="agent_2")
+    agent_3 = Agent(name="agent_3")
+
+    # Create main agent with mixed enabled/disabled handoffs
+    main_agent = Agent(
+        name="main_agent",
+        handoffs=[
+            handoff(agent_1, is_enabled=True),  # enabled
+            handoff(agent_2, is_enabled=False),  # disabled
+            handoff(agent_3, is_enabled=lambda ctx, agent: True),  # enabled callable
+        ],
+    )
+
+    context_wrapper = RunContextWrapper(main_agent)
+
+    # Get filtered handoffs using the runner's method
+    filtered_handoffs = await AgentRunner._get_handoffs(main_agent, context_wrapper)
+
+    # Should only have 2 handoffs (agent_1 and agent_3), agent_2 should be filtered out
+    assert len(filtered_handoffs) == 2
+
+    # Check that the correct agents are present
+    agent_names = {h.agent_name for h in filtered_handoffs}
+    assert agent_names == {"agent_1", "agent_3"}
+    assert "agent_2" not in agent_names

tests/test_run_step_execution.py

@@ -325,7 +325,7 @@ async def get_execute_result(
     run_config: RunConfig | None = None,
 ) -> SingleStepResult:
     output_schema = AgentRunner._get_output_schema(agent)
-    handoffs = AgentRunner._get_handoffs(agent)
+    handoffs = await AgentRunner._get_handoffs(agent, context_wrapper or RunContextWrapper(None))
 
     processed_response = RunImpl.process_model_response(
         agent=agent,

tests/test_run_step_processing.py

@@ -186,7 +186,7 @@ async def test_handoffs_parsed_correctly():
         agent=agent_3,
         response=response,
         output_schema=None,
-        handoffs=AgentRunner._get_handoffs(agent_3),
+        handoffs=await AgentRunner._get_handoffs(agent_3, _dummy_ctx()),
         all_tools=await agent_3.get_all_tools(_dummy_ctx()),
     )
     assert len(result.handoffs) == 1, "Should have a handoff here"
@@ -216,7 +216,7 @@ async def test_missing_handoff_fails():
             agent=agent_3,
             response=response,
             output_schema=None,
-            handoffs=AgentRunner._get_handoffs(agent_3),
+            handoffs=await AgentRunner._get_handoffs(agent_3, _dummy_ctx()),
             all_tools=await agent_3.get_all_tools(_dummy_ctx()),
         )
 
@@ -239,7 +239,7 @@ async def test_multiple_handoffs_doesnt_error():
         agent=agent_3,
         response=response,
         output_schema=None,
-        handoffs=AgentRunner._get_handoffs(agent_3),
+        handoffs=await AgentRunner._get_handoffs(agent_3, _dummy_ctx()),
         all_tools=await agent_3.get_all_tools(_dummy_ctx()),
     )
     assert len(result.handoffs) == 2, "Should have multiple handoffs here"
@@ -471,7 +471,7 @@ async def test_tool_and_handoff_parsed_correctly():
         agent=agent_3,
         response=response,
         output_schema=None,
-        handoffs=AgentRunner._get_handoffs(agent_3),
+        handoffs=await AgentRunner._get_handoffs(agent_3, _dummy_ctx()),
         all_tools=await agent_3.get_all_tools(_dummy_ctx()),
     )
     assert result.functions and len(result.functions) == 1