diff --git a/py/src/braintrust/integrations/anthropic/test_anthropic.py b/py/src/braintrust/integrations/anthropic/test_anthropic.py
index 588a5c5e..5fbbeac3 100644
--- a/py/src/braintrust/integrations/anthropic/test_anthropic.py
+++ b/py/src/braintrust/integrations/anthropic/test_anthropic.py
@@ -304,6 +304,7 @@ def test_anthropic_beta_messages_create_captures_context_and_usage_metadata(memo
     span = find_span_by_name(memory_logger.pop(), "anthropic.messages.create")
     assert "error" not in span
     assert span["metadata"]["context_management"] == {"edits": [{"type": "clear_thinking_20251015", "keep": "all"}]}
+    assert span["metadata"]["speed"] == "standard"
     assert span["metadata"]["usage_speed"] == response.usage.speed == "standard"
 
 
diff --git a/py/src/braintrust/integrations/anthropic/tracing.py b/py/src/braintrust/integrations/anthropic/tracing.py
index 27ea2220..6aa0a29f 100644
--- a/py/src/braintrust/integrations/anthropic/tracing.py
+++ b/py/src/braintrust/integrations/anthropic/tracing.py
@@ -67,6 +67,7 @@ def _accumulate_event_parameters(accumulator) -> set[str]:
     "model",
     "max_tokens",
     "temperature",
+    "speed",
     "top_k",
     "top_p",
     "stop_sequences",