diff --git a/internal/translator/openai/claude/openai_claude_response.go b/internal/translator/openai/claude/openai_claude_response.go
index 47f3f389..bdd0dfc6 100644
--- a/internal/translator/openai/claude/openai_claude_response.go
+++ b/internal/translator/openai/claude/openai_claude_response.go
@@ -336,7 +336,7 @@ func convertOpenAIStreamingChunkToAnthropic(rawJSON []byte, param *ConvertOpenAI
 
 	// Handle usage information separately (this comes in a later chunk)
 	// Only process if usage has actual values (not null)
-	if param.FinishReason != "" {
+	if param.FinishReason != "" && !param.MessageDeltaSent {
 		usage := root.Get("usage")
 		var inputTokens, outputTokens, cachedTokens int64
 		if usage.Exists() && usage.Type != gjson.Null {
diff --git a/internal/translator/openai/claude/openai_claude_response_test.go b/internal/translator/openai/claude/openai_claude_response_test.go
index 35aa36f3..f5b063b2 100644
--- a/internal/translator/openai/claude/openai_claude_response_test.go
+++ b/internal/translator/openai/claude/openai_claude_response_test.go
@@ -103,6 +103,25 @@ func lastStopReason(events []sseEvent) string {
 
 const streamReq = `{"stream":true}`
 
+func TestStreaming_LateUsageOnlyDoesNotEmitAfterMessageStop(t *testing.T) {
+	events := runStream(t, streamReq,
+		`{"id":"c1","model":"m","choices":[{"index":0,"delta":{"role":"assistant"},"finish_reason":null}]}`,
+		`{"id":"c1","model":"m","choices":[{"index":0,"delta":{"content":"hello"},"finish_reason":null}]}`,
+		`{"id":"c1","model":"m","choices":[{"index":0,"delta":{},"finish_reason":"stop"}],"usage":{"prompt_tokens":1,"completion_tokens":1}}`,
+		`{"id":"c1","model":"m","choices":[],"usage":{"prompt_tokens":1,"completion_tokens":1}}`,
+	)
+
+	if got := countByType(events, "message_delta"); got != 1 {
+		t.Fatalf("expected exactly one message_delta, got %d (events=%+v)", got, events)
+	}
+	if got := countByType(events, "message_stop"); got != 1 {
+		t.Fatalf("expected exactly one message_stop, got %d (events=%+v)", got, events)
+	}
+	if len(events) == 0 || events[len(events)-1].Type != "message_stop" {
+		t.Fatalf("message_stop must be the last semantic event (events=%+v)", events)
+	}
+}
+
 func TestConvertOpenAIResponseToClaude_StreamIgnoresNullToolNameDelta(t *testing.T) {
 	originalRequest := []byte(streamReq)
 	var param any