diff --git a/benchmark/agbenchmark/reports/processing/process_report.py b/benchmark/agbenchmark/reports/processing/process_report.py
index 1f73ed3c0b..57a2ee4fb2 100644
--- a/benchmark/agbenchmark/reports/processing/process_report.py
+++ b/benchmark/agbenchmark/reports/processing/process_report.py
@@ -46,7 +46,7 @@ def get_agent_category(report: Report) -> dict[str, Any]:
             ):
                 continue
             categories.setdefault(category, 0)
-            if data.metrics.success:
+            if data.metrics.success and data.metrics.difficulty:
                 num_dif = STRING_DIFFICULTY_MAP[data.metrics.difficulty]
                 if num_dif > categories[category]:
                     categories[category] = num_dif
diff --git a/benchmark/agbenchmark/reports/processing/report_types.py b/benchmark/agbenchmark/reports/processing/report_types.py
index 3ba9e6c6bf..e462ce2811 100644
--- a/benchmark/agbenchmark/reports/processing/report_types.py
+++ b/benchmark/agbenchmark/reports/processing/report_types.py
@@ -1,48 +1,38 @@
-from typing import Any, Dict, List, Union
+from typing import Any, Dict, List
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, constr, validator
 
 datetime_format = r"^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\+00:00$"
-from pydantic import BaseModel, constr
 
 
-class ForbidOptionalMeta(type(BaseModel)):  # metaclass to forbid optional fields
-    def __new__(cls, name: str, bases: tuple, dct: Dict[str, Any]) -> Any:
-        for attr_name, attr_value in dct.items():
-            if (
-                getattr(attr_value, "__origin__", None) == Union
-                and type(None) in attr_value.__args__
-            ):
-                raise TypeError(
-                    f"Optional fields are forbidden, but found in {attr_name}"
-                )
-
-        return super().__new__(cls, name, bases, dct)
-
-
-class BaseModelBenchmark(BaseModel, metaclass=ForbidOptionalMeta):
-    class Config:
-        extra = "forbid"
-
-
-class Metrics(BaseModelBenchmark):
-    difficulty: str
-    success: bool
-    success_percentage: float = Field(..., alias="success_%")
-    run_time: str
-    fail_reason: str | None
+class Metrics(BaseModel):
+    difficulty: str | None
+    success: bool | None = None
+    run_time: str | None = None
+    fail_reason: str | None = None
+    success_percentage: float | None = Field(default=None, alias="success_%")
     attempted: bool
-    cost: float | None
+    cost: float | None = None
+
+    @validator("attempted")
+    def require_metrics_if_attempted(cls, v: bool, values: dict[str, Any]):
+        required_fields_if_attempted = ["success", "run_time"]
+        if v:
+            for f in required_fields_if_attempted:
+                assert (
+                    values.get(f) is not None
+                ), f"'{f}' must be defined if attempted is True"
+        return v
 
 
-class MetricsOverall(BaseModelBenchmark):
+class MetricsOverall(BaseModel):
     run_time: str
     highest_difficulty: str
-    percentage: float | None
-    total_cost: float | None
+    percentage: float | None = None
+    total_cost: float | None = None
 
 
-class Test(BaseModelBenchmark):
+class Test(BaseModel):
     data_path: str
     is_regression: bool
     answer: str
@@ -50,19 +40,19 @@ class Test(BaseModelBenchmark):
     metrics: Metrics
     category: List[str]
     task: str
-    reached_cutoff: bool
-    metadata: Any
+    reached_cutoff: bool | None = None  # None if in progress
+    metadata: dict[str, Any] | None = Field(default_factory=dict)
 
 
-class ReportBase(BaseModelBenchmark):
+class ReportBase(BaseModel):
     command: str
-    completion_time: str | None
+    completion_time: str | None = None
     benchmark_start_time: constr(regex=datetime_format)
     metrics: MetricsOverall
     config: Dict[str, str | dict[str, str]]
-    agent_git_commit_sha: str | None
-    benchmark_git_commit_sha: str | None
-    repo_url: str | None
+    agent_git_commit_sha: str | None = None
+    benchmark_git_commit_sha: str | None = None
+    repo_url: str | None = None
 
 
 class Report(ReportBase):