feat: Remove overall_eval_status calculation from _CustomMetricEvaluator and add threshold to custom metric function expected signature

Co-authored-by: Joseph Pagadora <jcpagadora@google.com>
PiperOrigin-RevId: 861268984

src/google/adk/evaluation/custom_metric_evaluator.py

@@ -24,7 +24,6 @@ from typing_extensions import override
 from .eval_case import ConversationScenario
 from .eval_case import Invocation
 from .eval_metrics import EvalMetric
-from .eval_metrics import EvalStatus
 from .evaluator import EvaluationResult
 from .evaluator import Evaluator
 
@@ -44,12 +43,6 @@ def _get_metric_function(
     ) from e
 
 
-def _get_eval_status(score: Optional[float], threshold: float) -> EvalStatus:
-  if score is None:
-    return EvalStatus.NOT_EVALUATED
-  return EvalStatus.PASSED if score >= threshold else EvalStatus.FAILED
-
-
 class _CustomMetricEvaluator(Evaluator):
   """Evaluator for custom metrics."""
 
@@ -64,16 +57,20 @@ class _CustomMetricEvaluator(Evaluator):
       expected_invocations: Optional[list[Invocation]],
       conversation_scenario: Optional[ConversationScenario] = None,
   ) -> EvaluationResult:
+    eval_metric = self._eval_metric.model_copy(deep=True)
+    eval_metric.threshold = None
     if inspect.iscoroutinefunction(self._metric_function):
       eval_result = await self._metric_function(
-          actual_invocations, expected_invocations, conversation_scenario
+          eval_metric,
+          actual_invocations,
+          expected_invocations,
+          conversation_scenario,
       )
     else:
       eval_result = self._metric_function(
-          actual_invocations, expected_invocations, conversation_scenario
+          eval_metric,
+          actual_invocations,
+          expected_invocations,
+          conversation_scenario,
       )
-
-    eval_result.overall_eval_status = _get_eval_status(
-        eval_result.overall_score, self._eval_metric.threshold
-    )
     return eval_result

src/google/adk/evaluation/eval_metrics.py

@@ -258,9 +258,11 @@ class EvalMetric(EvalBaseModel):
       description="The name of the metric.",
   )
 
-  threshold: float = Field(
+  threshold: Optional[float] = Field(
+      default=None,
       description=(
-          "A threshold value. Each metric decides how to interpret this"
+          "This field will be deprecated soon. Please use `criterion` instead."
+          " A threshold value. Each metric decides how to interpret this"
           " threshold."
       ),
   )