diff --git a/plugins/wasm-go/extensions/ai-proxy/provider/vertex.go b/plugins/wasm-go/extensions/ai-proxy/provider/vertex.go
index 7c7769cad..460ede929 100644
--- a/plugins/wasm-go/extensions/ai-proxy/provider/vertex.go
+++ b/plugins/wasm-go/extensions/ai-proxy/provider/vertex.go
@@ -17,6 +17,7 @@ import (
 	"time"
 
 	"github.com/alibaba/higress/plugins/wasm-go/extensions/ai-proxy/util"
+	"github.com/google/uuid"
 	"github.com/higress-group/proxy-wasm-go-sdk/proxywasm"
 	"github.com/higress-group/proxy-wasm-go-sdk/proxywasm/types"
 	"github.com/higress-group/wasm-go/pkg/log"
@@ -47,6 +48,7 @@ const (
 	contextOpenAICompatibleMarker      = "isOpenAICompatibleRequest"
 	contextVertexRawMarker             = "isVertexRawRequest"
 	contextVertexStreamDoneMarker      = "vertexStreamDoneSent"
+	contextVertexStreamToolCallIDs     = "vertexStreamToolCallIDs"
 	vertexAnthropicVersion             = "vertex-2023-10-16"
 	vertexImageVariationDefaultPrompt  = "Create variations of the provided image."
 )
@@ -871,6 +873,7 @@ func (v *vertexProvider) buildChatCompletionResponse(ctx wrapper.HttpContext, re
 				args, _ := json.Marshal(part.FunctionCall.Args)
 				choice.Message.ToolCalls = []toolCall{
 					{
+						Id:               newOpenAIToolCallID(),
 						Type:             "function",
 						ThoughtSignature: part.ThoughtSignature,
 						ExtraContent:     buildGoogleThoughtSignatureExtraContent(part.ThoughtSignature),
@@ -981,6 +984,7 @@ func (v *vertexProvider) buildChatCompletionStreamResponse(ctx wrapper.HttpConte
 			choice.Delta = &chatMessage{
 				ToolCalls: []toolCall{
 					{
+						Id:               getVertexStreamToolCallID(ctx, 0),
 						Type:             "function",
 						ThoughtSignature: part.ThoughtSignature,
 						ExtraContent:     buildGoogleThoughtSignatureExtraContent(part.ThoughtSignature),
@@ -1025,6 +1029,24 @@ func (v *vertexProvider) buildChatCompletionStreamResponse(ctx wrapper.HttpConte
 	return &streamResponse
 }
 
+func newOpenAIToolCallID() string {
+	return fmt.Sprintf("call_%s", uuid.New().String())
+}
+
+func getVertexStreamToolCallID(ctx wrapper.HttpContext, index int) string {
+	toolCallIDs, _ := ctx.GetContext(contextVertexStreamToolCallIDs).(map[int]string)
+	if toolCallIDs == nil {
+		toolCallIDs = make(map[int]string)
+		ctx.SetContext(contextVertexStreamToolCallIDs, toolCallIDs)
+	}
+	if id := toolCallIDs[index]; id != "" {
+		return id
+	}
+	id := newOpenAIToolCallID()
+	toolCallIDs[index] = id
+	return id
+}
+
 func (v *vertexProvider) appendResponse(responseBuilder *strings.Builder, responseBody string) {
 	responseBuilder.WriteString(fmt.Sprintf("%s %s\n\n", streamDataItemKey, responseBody))
 }
diff --git a/plugins/wasm-go/extensions/ai-proxy/provider/vertex_test.go b/plugins/wasm-go/extensions/ai-proxy/provider/vertex_test.go
index d7a88b333..51fad3477 100644
--- a/plugins/wasm-go/extensions/ai-proxy/provider/vertex_test.go
+++ b/plugins/wasm-go/extensions/ai-proxy/provider/vertex_test.go
@@ -2,6 +2,7 @@ package provider
 
 import (
 	"net/http"
+	"strings"
 	"testing"
 
 	"github.com/alibaba/higress/plugins/wasm-go/extensions/ai-proxy/util"
@@ -609,6 +610,8 @@ func TestVertexProviderPreservesFunctionCallThoughtSignature(t *testing.T) {
 	require.Len(t, response.Choices, 1)
 	require.NotNil(t, response.Choices[0].Message)
 	require.Len(t, response.Choices[0].Message.ToolCalls, 1)
+	assert.NotEmpty(t, response.Choices[0].Message.ToolCalls[0].Id)
+	assert.True(t, strings.HasPrefix(response.Choices[0].Message.ToolCalls[0].Id, "call_"))
 	assert.Equal(t, "thought-signature-from-vertex", response.Choices[0].Message.ToolCalls[0].ThoughtSignature)
 	assert.Equal(
 		t,
@@ -617,6 +620,48 @@ func TestVertexProviderPreservesFunctionCallThoughtSignature(t *testing.T) {
 	)
 }
 
+func TestVertexProviderStreamToolCallIncludesStableID(t *testing.T) {
+	v := &vertexProvider{}
+	ctx := newMockMultipartHttpContext()
+	ctx.SetContext(ctxKeyFinalRequestModel, "gemini-3.1-pro-preview")
+	vertexResp := &vertexChatResponse{
+		ResponseId: "vertex-response-id",
+		Candidates: []vertexChatCandidate{
+			{
+				Index: 0,
+				Content: vertexChatContent{
+					Role: "model",
+					Parts: []vertexPart{
+						{
+							FunctionCall: &vertexFunctionCall{
+								Name: "lookup",
+								Args: map[string]interface{}{"query": "test"},
+							},
+							ThoughtSignature: "thought-signature-from-vertex",
+						},
+					},
+				},
+				FinishReason: "STOP",
+			},
+		},
+	}
+
+	first := v.buildChatCompletionStreamResponse(ctx, vertexResp)
+	second := v.buildChatCompletionStreamResponse(ctx, vertexResp)
+
+	require.Len(t, first.Choices, 1)
+	require.NotNil(t, first.Choices[0].Delta)
+	require.Len(t, first.Choices[0].Delta.ToolCalls, 1)
+	firstID := first.Choices[0].Delta.ToolCalls[0].Id
+	assert.NotEmpty(t, firstID)
+	assert.True(t, strings.HasPrefix(firstID, "call_"))
+
+	require.Len(t, second.Choices, 1)
+	require.NotNil(t, second.Choices[0].Delta)
+	require.Len(t, second.Choices[0].Delta.ToolCalls, 1)
+	assert.Equal(t, firstID, second.Choices[0].Delta.ToolCalls[0].Id)
+}
+
 func TestVertexProviderRestoresFunctionCallThoughtSignature(t *testing.T) {
 	v := &vertexProvider{}
 	req := &chatCompletionRequest{