Agent inputs default values

Author: cesarebernardis

docs/wayflowcore/source/core/changelog.rst

@@ -39,6 +39,12 @@ Possibly Breaking Changes
 Bug fixes
 ^^^^^^^^^
 
+* **Default values in agents inputs were ignored:**
+
+  Fixed a bug where if agents had input descriptors with default values set, these defaults were ignored and not
+  used when starting a conversation. Now default values of input descriptors are used if they are set, and no
+  input entry with the descriptor name is passed to the ``start_conversation`` method.
+
 * **Default values in tools outputs were ignored:**
 
   Fixed a bug where if tools had multiple output descriptors with default values set for some of them, these defaults were ignored and not

wayflowcore/src/wayflowcore/agent.py

@@ -18,7 +18,7 @@
 from wayflowcore.idgeneration import IdGenerator
 from wayflowcore.messagelist import Message, MessageList
 from wayflowcore.models.llmmodel import LlmModel
-from wayflowcore.property import Property, _cast_value_into
+from wayflowcore.property import Property, _cast_value_into, _empty_default
 from wayflowcore.serialization.serializer import SerializableDataclassMixin, SerializableObject
 from wayflowcore.templates import PromptTemplate
 from wayflowcore.tools import DescribedAgent, DescribedFlow, Tool, ToolBox
@@ -398,19 +398,32 @@ def start_conversation(
         if not isinstance(messages, MessageList):
             messages = MessageList.from_messages(messages=messages)
 
+        required_input_names = [
+            input_descriptor.name
+            for input_descriptor in self.input_descriptors
+            if input_descriptor.default_value is _empty_default
+        ]
+
         if len(self.input_descriptors) > 0:
             if inputs is None:
-                raise ValueError(
-                    f"Agent has inputs (`{self.input_descriptors}`), but you did not pass any."
-                )
+                if required_input_names:
+                    raise ValueError(
+                        f"Agent requires inputs (`{required_input_names}`), but you did not pass any."
+                    )
+                else:
+                    # We don't have inputs, but all the input descriptors have defaults
+                    inputs = {}
             for input_value_description in self.input_descriptors:
-                if input_value_description.name not in inputs:
+                # We retrieve inputs when available, otherwise get defaults if defined, if not defined, raise
+                if input_value_description.name in inputs:
+                    input_value = inputs[input_value_description.name]
+                elif input_value_description.default_value is not _empty_default:
+                    input_value = input_value_description.default_value
+                else:
                     raise ValueError(
-                        f"The agent has an input `{input_value_description}`, but it was not passed in the input dictionary: `{inputs}`"
+                        f"The agent requires an input `{input_value_description.name}`, but it was not passed in the input dictionary: `{inputs}`"
                     )
 
-                input_value = inputs[input_value_description.name]
-
                 try:
                     casted_input_value = _cast_value_into(input_value, input_value_description)
                     inputs[input_value_description.name] = casted_input_value

wayflowcore/tests/integration/steps/test_agentexecution_step.py

@@ -14,7 +14,7 @@
 from wayflowcore.flow import Flow
 from wayflowcore.flowhelpers import create_single_step_flow, run_flow_and_return_outputs
 from wayflowcore.models.vllmmodel import VllmModel
-from wayflowcore.property import IntegerProperty, Property
+from wayflowcore.property import IntegerProperty, Property, StringProperty
 from wayflowcore.steps.agentexecutionstep import AgentExecutionStep, CallerInputMode
 from wayflowcore.steps.outputmessagestep import OutputMessageStep
 from wayflowcore.tools import ClientTool, ToolRequest
@@ -495,3 +495,49 @@ def test_agent_step_uses_default_caller_input_mode_of_agent(remotely_hosted_llm)
     conv.append_user_message("What is the capital of Switzerland?")
     status = conv.execute()
     assert isinstance(status, FinishedStatus)
+
+
+@retry_test(max_attempts=3)
+def test_agent_step_that_uses_agent_with_default_input_values_works(big_llama):
+    """
+    Failure rate:          0 out of 20
+    Observed on:           2025-11-19
+    Average success time:  2.94 seconds per successful attempt
+    Average failure time:  No time measurement
+    Max attempt:           3
+    Justification:         (0.05 ** 3) ~= 9.4 / 100'000
+    """
+    agent = Agent(
+        llm=big_llama,
+        custom_instruction="You are a helpful agent. Here's what you know: {{context}}. Answer the user `{{username}}`.",
+        input_descriptors=[
+            StringProperty(name="context", default_value="Videogames"),
+            StringProperty(name="username"),
+        ],
+    )
+
+    agent_step = AgentExecutionStep(
+        agent=agent,
+    )
+
+    flow = Flow.from_steps(steps=[agent_step])
+    assert len(flow.input_descriptors) == 2
+    assert {"context", "username"} == set(descriptor.name for descriptor in flow.input_descriptors)
+    context_input = next(
+        descriptor for descriptor in flow.input_descriptors if descriptor.name == "context"
+    )
+    assert context_input.default_value == "Videogames"
+
+    conv = flow.start_conversation({"username": "john"})
+    status = conv.execute()
+    assert isinstance(status, UserMessageRequestStatus)
+    status.submit_user_response("Who is the user?")
+    status = conv.execute()
+    assert isinstance(status, UserMessageRequestStatus)
+    last_message = status.message
+    assert "john" in last_message.content.lower()
+    status.submit_user_response("What do you know?")
+    status = conv.execute()
+    assert isinstance(status, UserMessageRequestStatus)
+    last_message = status.message
+    assert "videogame" in last_message.content.lower()

wayflowcore/tests/integration/test_agent.py

@@ -2080,3 +2080,57 @@ def test_caller_input_mode_never_with_single_iteration(big_llama):
     status = conv.execute()
     assert isinstance(status, FinishedStatus)
     assert not status.output_values["haiku_submitted"]
+
+
+@retry_test(max_attempts=3)
+def test_agent_with_default_input_values_works(big_llama):
+    """
+    Failure rate:          0 out of 20
+    Observed on:           2025-11-19
+    Average success time:  2.81 seconds per successful attempt
+    Average failure time:  No time measurement
+    Max attempt:           3
+    Justification:         (0.05 ** 3) ~= 9.4 / 100'000
+    """
+    agent = Agent(
+        llm=big_llama,
+        custom_instruction="You are a helpful agent. Here's what you know: {{context}}. Answer the user `{{username}}`.",
+        input_descriptors=[
+            StringProperty(name="context", default_value="Videogames"),
+            StringProperty(name="username"),
+        ],
+    )
+    conv = agent.start_conversation({"username": "john"})
+    status = conv.execute()
+    assert isinstance(status, UserMessageRequestStatus)
+    status.submit_user_response("Who is the user?")
+    status = conv.execute()
+    assert isinstance(status, UserMessageRequestStatus)
+    last_message = status.message
+    assert "john" in last_message.content.lower()
+    status.submit_user_response("What do you know?")
+    status = conv.execute()
+    assert isinstance(status, UserMessageRequestStatus)
+    last_message = status.message
+    assert "videogame" in last_message.content.lower()
+
+
+def test_agent_with_missing_input_values_raises(big_llama):
+    agent = Agent(
+        llm=big_llama,
+        custom_instruction="You are a helpful agent. Here's what you know: {{context}}. But also {{additional_context}}. Answer the user.",
+        input_descriptors=[
+            StringProperty(name="context", default_value="Videogames"),
+            StringProperty(name="additional_context"),
+        ],
+    )
+    with pytest.raises(
+        ValueError,
+        match=r"Agent requires inputs \(`\['additional_context'\]`\), but you did not pass any.",
+    ):
+        _ = agent.start_conversation()
+    with pytest.raises(
+        ValueError,
+        match="The agent requires an input `additional_context`, but it was not passed in the input dictionary",
+    ):
+        _ = agent.start_conversation({})