diff --git a/relay/channel/gemini/relay-gemini.go b/relay/channel/gemini/relay-gemini.go
index 65e5aa985..c76b5c247 100644
--- a/relay/channel/gemini/relay-gemini.go
+++ b/relay/channel/gemini/relay-gemini.go
@@ -1141,6 +1141,8 @@ func GeminiChatStreamHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *
 	id := helper.GetResponseID(c)
 	createAt := common.GetTimestamp()
 	finishReason := constant.FinishReasonStop
+	toolCallIndexByChoice := make(map[int]map[string]int)
+	nextToolCallIndexByChoice := make(map[int]int)
 
 	usage, err := geminiStreamHandler(c, info, resp, func(data string, geminiResponse *dto.GeminiChatResponse) bool {
 		response, isStop := streamResponseGeminiChat2OpenAI(geminiResponse)
@@ -1148,6 +1150,28 @@ func GeminiChatStreamHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *
 		response.Id = id
 		response.Created = createAt
 		response.Model = info.UpstreamModelName
+		for choiceIdx := range response.Choices {
+			choiceKey := response.Choices[choiceIdx].Index
+			for toolIdx := range response.Choices[choiceIdx].Delta.ToolCalls {
+				tool := &response.Choices[choiceIdx].Delta.ToolCalls[toolIdx]
+				if tool.ID == "" {
+					continue
+				}
+				m := toolCallIndexByChoice[choiceKey]
+				if m == nil {
+					m = make(map[string]int)
+					toolCallIndexByChoice[choiceKey] = m
+				}
+				if idx, ok := m[tool.ID]; ok {
+					tool.SetIndex(idx)
+					continue
+				}
+				idx := nextToolCallIndexByChoice[choiceKey]
+				nextToolCallIndexByChoice[choiceKey] = idx + 1
+				m[tool.ID] = idx
+				tool.SetIndex(idx)
+			}
+		}
 
 		logger.LogDebug(c, fmt.Sprintf("info.SendResponseCount = %d", info.SendResponseCount))
 		if info.SendResponseCount == 0 {