diff --git a/internal/translator/gemini-cli/openai/chat-completions/cli_openai_request.go b/internal/translator/gemini-cli/openai/chat-completions/cli_openai_request.go
index d4a453f3..6ed48486 100644
--- a/internal/translator/gemini-cli/openai/chat-completions/cli_openai_request.go
+++ b/internal/translator/gemini-cli/openai/chat-completions/cli_openai_request.go
@@ -26,6 +26,20 @@ import (
 //   - []byte: The transformed request data in Gemini CLI API format
 func ConvertOpenAIRequestToGeminiCLI(modelName string, inputRawJSON []byte, _ bool) []byte {
 	rawJSON := bytes.Clone(inputRawJSON)
+	var pathsToDelete []string
+	root := gjson.ParseBytes(rawJSON)
+	util.Walk(root, "", "additionalProperties", &pathsToDelete)
+	util.Walk(root, "", "$schema", &pathsToDelete)
+	util.Walk(root, "", "ref", &pathsToDelete)
+
+	var err error
+	for _, p := range pathsToDelete {
+		rawJSON, err = sjson.DeleteBytes(rawJSON, p)
+		if err != nil {
+			continue
+		}
+	}
+
 	// Base envelope
 	out := []byte(`{"project":"","request":{"contents":[],"generationConfig":{"thinkingConfig":{"include_thoughts":true}}},"model":"gemini-2.5-pro"}`)
 
@@ -232,7 +246,7 @@ func ConvertOpenAIRequestToGeminiCLI(modelName string, inputRawJSON []byte, _ bo
 	}
 
 	var pathsToType []string
-	root := gjson.ParseBytes(out)
+	root = gjson.ParseBytes(out)
 	util.Walk(root, "", "type", &pathsToType)
 	for _, p := range pathsToType {
 		typeResult := gjson.GetBytes(out, p)
diff --git a/internal/translator/gemini-cli/openai/chat-completions/cli_openai_response.go b/internal/translator/gemini-cli/openai/chat-completions/cli_openai_response.go
index 86ea6b69..15f528cc 100644
--- a/internal/translator/gemini-cli/openai/chat-completions/cli_openai_response.go
+++ b/internal/translator/gemini-cli/openai/chat-completions/cli_openai_response.go
@@ -20,6 +20,7 @@ import (
 // convertCliResponseToOpenAIChatParams holds parameters for response conversion.
 type convertCliResponseToOpenAIChatParams struct {
 	UnixTimestamp int64
+	FunctionIndex int
 }
 
 // ConvertCliResponseToOpenAI translates a single chunk of a streaming response from the
@@ -40,6 +41,7 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 	if *param == nil {
 		*param = &convertCliResponseToOpenAIChatParams{
 			UnixTimestamp: 0,
+			FunctionIndex: 0,
 		}
 	}
 
@@ -117,13 +119,18 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 			} else if functionCallResult.Exists() {
 				// Handle function call content.
 				toolCallsResult := gjson.Get(template, "choices.0.delta.tool_calls")
-				if !toolCallsResult.Exists() || !toolCallsResult.IsArray() {
+				functionCallIndex := (*param).(*convertCliResponseToOpenAIChatParams).FunctionIndex
+				(*param).(*convertCliResponseToOpenAIChatParams).FunctionIndex++
+				if toolCallsResult.Exists() && toolCallsResult.IsArray() {
+					functionCallIndex = len(toolCallsResult.Array())
+				} else {
 					template, _ = sjson.SetRaw(template, "choices.0.delta.tool_calls", `[]`)
 				}
 
-				functionCallTemplate := `{"id": "","type": "function","function": {"name": "","arguments": ""}}`
+				functionCallTemplate := `{"id": "","index": 0,"type": "function","function": {"name": "","arguments": ""}}`
 				fcName := functionCallResult.Get("name").String()
 				functionCallTemplate, _ = sjson.Set(functionCallTemplate, "id", fmt.Sprintf("%s-%d", fcName, time.Now().UnixNano()))
+				functionCallTemplate, _ = sjson.Set(functionCallTemplate, "index", functionCallIndex)
 				functionCallTemplate, _ = sjson.Set(functionCallTemplate, "function.name", fcName)
 				if fcArgsResult := functionCallResult.Get("args"); fcArgsResult.Exists() {
 					functionCallTemplate, _ = sjson.Set(functionCallTemplate, "function.arguments", fcArgsResult.Raw)
diff --git a/internal/translator/gemini/openai/chat-completions/gemini_openai_request.go b/internal/translator/gemini/openai/chat-completions/gemini_openai_request.go
index 50f8f1b7..447bba31 100644
--- a/internal/translator/gemini/openai/chat-completions/gemini_openai_request.go
+++ b/internal/translator/gemini/openai/chat-completions/gemini_openai_request.go
@@ -26,6 +26,20 @@ import (
 //   - []byte: The transformed request data in Gemini API format
 func ConvertOpenAIRequestToGemini(modelName string, inputRawJSON []byte, _ bool) []byte {
 	rawJSON := bytes.Clone(inputRawJSON)
+	var pathsToDelete []string
+	root := gjson.ParseBytes(rawJSON)
+	util.Walk(root, "", "additionalProperties", &pathsToDelete)
+	util.Walk(root, "", "$schema", &pathsToDelete)
+	util.Walk(root, "", "ref", &pathsToDelete)
+
+	var err error
+	for _, p := range pathsToDelete {
+		rawJSON, err = sjson.DeleteBytes(rawJSON, p)
+		if err != nil {
+			continue
+		}
+	}
+
 	// Base envelope
 	out := []byte(`{"contents":[],"generationConfig":{"thinkingConfig":{"include_thoughts":true}}}`)
 
@@ -257,7 +271,7 @@ func ConvertOpenAIRequestToGemini(modelName string, inputRawJSON []byte, _ bool)
 	}
 
 	var pathsToType []string
-	root := gjson.ParseBytes(out)
+	root = gjson.ParseBytes(out)
 	util.Walk(root, "", "type", &pathsToType)
 	for _, p := range pathsToType {
 		typeResult := gjson.GetBytes(out, p)
diff --git a/internal/translator/gemini/openai/chat-completions/gemini_openai_response.go b/internal/translator/gemini/openai/chat-completions/gemini_openai_response.go
index ab6cc19e..5f1161af 100644
--- a/internal/translator/gemini/openai/chat-completions/gemini_openai_response.go
+++ b/internal/translator/gemini/openai/chat-completions/gemini_openai_response.go
@@ -19,6 +19,7 @@ import (
 // convertGeminiResponseToOpenAIChatParams holds parameters for response conversion.
 type convertGeminiResponseToOpenAIChatParams struct {
 	UnixTimestamp int64
+	FunctionIndex int
 }
 
 // ConvertGeminiResponseToOpenAI translates a single chunk of a streaming response from the
@@ -39,6 +40,7 @@ func ConvertGeminiResponseToOpenAI(_ context.Context, _ string, originalRequestR
 	if *param == nil {
 		*param = &convertGeminiResponseToOpenAIChatParams{
 			UnixTimestamp: 0,
+			FunctionIndex: 0,
 		}
 	}
 
@@ -120,13 +122,18 @@ func ConvertGeminiResponseToOpenAI(_ context.Context, _ string, originalRequestR
 			} else if functionCallResult.Exists() {
 				// Handle function call content.
 				toolCallsResult := gjson.Get(template, "choices.0.delta.tool_calls")
-				if !toolCallsResult.Exists() || !toolCallsResult.IsArray() {
+				functionCallIndex := (*param).(*convertGeminiResponseToOpenAIChatParams).FunctionIndex
+				(*param).(*convertGeminiResponseToOpenAIChatParams).FunctionIndex++
+				if toolCallsResult.Exists() && toolCallsResult.IsArray() {
+					functionCallIndex = len(toolCallsResult.Array())
+				} else {
 					template, _ = sjson.SetRaw(template, "choices.0.delta.tool_calls", `[]`)
 				}
 
-				functionCallTemplate := `{"id": "","type": "function","function": {"name": "","arguments": ""}}`
+				functionCallTemplate := `{"id": "","index": 0,"type": "function","function": {"name": "","arguments": ""}}`
 				fcName := functionCallResult.Get("name").String()
 				functionCallTemplate, _ = sjson.Set(functionCallTemplate, "id", fmt.Sprintf("%s-%d", fcName, time.Now().UnixNano()))
+				functionCallTemplate, _ = sjson.Set(functionCallTemplate, "index", functionCallIndex)
 				functionCallTemplate, _ = sjson.Set(functionCallTemplate, "function.name", fcName)
 				if fcArgsResult := functionCallResult.Get("args"); fcArgsResult.Exists() {
 					functionCallTemplate, _ = sjson.Set(functionCallTemplate, "function.arguments", fcArgsResult.Raw)