diff --git a/hyperbrowser/client/managers/sandboxes/process_output.py b/hyperbrowser/client/managers/sandboxes/process_output.py
index ff1524e0..3184473e 100644
--- a/hyperbrowser/client/managers/sandboxes/process_output.py
+++ b/hyperbrowser/client/managers/sandboxes/process_output.py
@@ -26,13 +26,20 @@ def __init__(self, process_id: str, max_bytes: int):
         }
 
     def failure(
-        self, message: str, code: str = "incomplete_output"
+        self,
+        message: str,
+        code: str = "incomplete_output",
+        details: Optional[Dict[str, int]] = None,
     ) -> HyperbrowserError:
         return HyperbrowserError(
             message,
             code=code,
             service="runtime",
-            details={"process_id": self.process_id, "last_seq": self.seq},
+            details={
+                "process_id": self.process_id,
+                "last_seq": self.seq,
+                **(details or {}),
+            },
         )
 
     def consume(self, event) -> None:
@@ -51,8 +58,9 @@ def consume(self, event) -> None:
             self.size += len(raw)
             if self.size > self.max_bytes:
                 raise self.failure(
-                    "Command output exceeds max_output_bytes; increase the collection limit or disconnect a detached process",
+                    f"Command output exceeds max_output_bytes ({self.size} bytes received, limit {self.max_bytes}); increase the collection limit or disconnect a detached process",
                     "output_limit_exceeded",
+                    {"max_output_bytes": self.max_bytes, "received_bytes": self.size},
                 )
             self.seq = data["seq"]
             text = self._decoders[stream].decode(raw)
diff --git a/tests/test_sandbox_process_collection.py b/tests/test_sandbox_process_collection.py
index 1171bf04..096d3c87 100644
--- a/tests/test_sandbox_process_collection.py
+++ b/tests/test_sandbox_process_collection.py
@@ -232,3 +232,13 @@ def test_invalid_collection_limit_rejected_before_start(limit):
     with pytest.raises(ValueError, match="positive integer"):
         SyncProcesses(transport).start("test", max_output_bytes=limit)
     assert not transport.calls
+
+
+def test_output_limit_error_reports_limit_and_received_bytes():
+    transport = SyncTransport([output(1, b"too much"), done(1)])
+    with pytest.raises(HyperbrowserError) as exc:
+        SyncProcesses(transport).exec("test", max_output_bytes=4)
+    assert exc.value.code == "output_limit_exceeded"
+    assert exc.value.details["max_output_bytes"] == 4
+    assert exc.value.details["received_bytes"] == 8
+    assert "8 bytes received, limit 4" in str(exc.value)