diff --git a/internal/translator/openai/gemini/openai_gemini_request.go b/internal/translator/openai/gemini/openai_gemini_request.go
index 7369de88..53773806 100644
--- a/internal/translator/openai/gemini/openai_gemini_request.go
+++ b/internal/translator/openai/gemini/openai_gemini_request.go
@@ -113,6 +113,7 @@ func ConvertGeminiRequestToOpenAI(modelName string, inputRawJSON []byte, stream
 
 	// Process contents (Gemini messages) -> OpenAI messages
 	var toolCallIDs []string // Track tool call IDs for matching with tool results
+	toolCallConsumeIdx := 0
 
 	// System instruction -> OpenAI system message
 	// Gemini may provide `systemInstruction` or `system_instruction`; support both keys.
@@ -241,12 +242,9 @@ func ConvertGeminiRequestToOpenAI(modelName string, inputRawJSON []byte, stream
 							}
 						}
 
-						// Try to match with previous tool call ID
-						_ = functionResponse.Get("name").String() // functionName not used for now
-						if len(toolCallIDs) > 0 {
-							// Use the last tool call ID (simple matching by function name)
-							// In a real implementation, you might want more sophisticated matching
-							toolMsg, _ = sjson.SetBytes(toolMsg, "tool_call_id", toolCallIDs[len(toolCallIDs)-1])
+						if toolCallConsumeIdx < len(toolCallIDs) {
+							toolMsg, _ = sjson.SetBytes(toolMsg, "tool_call_id", toolCallIDs[toolCallConsumeIdx])
+							toolCallConsumeIdx++
 						} else {
 							// Generate a tool call ID if none available
 							toolMsg, _ = sjson.SetBytes(toolMsg, "tool_call_id", genToolCallID())
diff --git a/internal/translator/openai/gemini/openai_gemini_request_test.go b/internal/translator/openai/gemini/openai_gemini_request_test.go
new file mode 100644
index 00000000..7bfbaad5
--- /dev/null
+++ b/internal/translator/openai/gemini/openai_gemini_request_test.go
@@ -0,0 +1,106 @@
+package gemini
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/tidwall/gjson"
+)
+
+func TestConvertGeminiRequestToOpenAI_FunctionResponsesConsumeToolCallIDsFIFO(t *testing.T) {
+	inputJSON := []byte(`{
+		"contents": [
+			{
+				"role": "model",
+				"parts": [
+					{"functionCall": {"name": "read_file", "args": {"path": "a.txt"}}},
+					{"functionCall": {"name": "grep", "args": {"pattern": "needle"}}},
+					{"functionCall": {"name": "list_dir", "args": {"path": "."}}}
+				]
+			},
+			{
+				"role": "function",
+				"parts": [
+					{"functionResponse": {"name": "read_file", "response": {"result": "a"}}},
+					{"functionResponse": {"name": "grep", "response": {"result": "b"}}},
+					{"functionResponse": {"name": "list_dir", "response": {"result": "c"}}}
+				]
+			}
+		]
+	}`)
+
+	out := ConvertGeminiRequestToOpenAI("test-model", inputJSON, false)
+	firstID := gjson.GetBytes(out, "messages.0.tool_calls.0.id").String()
+	secondID := gjson.GetBytes(out, "messages.0.tool_calls.1.id").String()
+	thirdID := gjson.GetBytes(out, "messages.0.tool_calls.2.id").String()
+
+	if firstID == "" || secondID == "" || thirdID == "" {
+		t.Fatalf("expected all assistant tool call IDs to be set. Output: %s", string(out))
+	}
+	if firstID == secondID || secondID == thirdID || firstID == thirdID {
+		t.Fatalf("expected distinct assistant tool call IDs, got %q, %q, %q", firstID, secondID, thirdID)
+	}
+	if got := gjson.GetBytes(out, "messages.1.tool_call_id").String(); got != firstID {
+		t.Fatalf("messages.1.tool_call_id = %q, want %q. Output: %s", got, firstID, string(out))
+	}
+	if got := gjson.GetBytes(out, "messages.2.tool_call_id").String(); got != secondID {
+		t.Fatalf("messages.2.tool_call_id = %q, want %q. Output: %s", got, secondID, string(out))
+	}
+	if got := gjson.GetBytes(out, "messages.3.tool_call_id").String(); got != thirdID {
+		t.Fatalf("messages.3.tool_call_id = %q, want %q. Output: %s", got, thirdID, string(out))
+	}
+}
+
+func TestConvertGeminiRequestToOpenAI_FunctionResponseWithoutPriorCallGetsFallbackID(t *testing.T) {
+	inputJSON := []byte(`{
+		"contents": [
+			{
+				"role": "function",
+				"parts": [
+					{"functionResponse": {"name": "read_file", "response": {"result": "ok"}}}
+				]
+			}
+		]
+	}`)
+
+	out := ConvertGeminiRequestToOpenAI("test-model", inputJSON, false)
+	toolCallID := gjson.GetBytes(out, "messages.0.tool_call_id").String()
+	if !strings.HasPrefix(toolCallID, "call_") {
+		t.Fatalf("fallback tool_call_id = %q, want call_ prefix. Output: %s", toolCallID, string(out))
+	}
+}
+
+func TestConvertGeminiRequestToOpenAI_ExtraFunctionResponsesUseFallbackID(t *testing.T) {
+	inputJSON := []byte(`{
+		"contents": [
+			{
+				"role": "model",
+				"parts": [
+					{"functionCall": {"name": "read_file", "args": {"path": "a.txt"}}}
+				]
+			},
+			{
+				"role": "function",
+				"parts": [
+					{"functionResponse": {"name": "read_file", "response": {"result": "a"}}},
+					{"functionResponse": {"name": "read_file", "response": {"result": "extra"}}}
+				]
+			}
+		]
+	}`)
+
+	out := ConvertGeminiRequestToOpenAI("test-model", inputJSON, false)
+	callID := gjson.GetBytes(out, "messages.0.tool_calls.0.id").String()
+	firstResponseID := gjson.GetBytes(out, "messages.1.tool_call_id").String()
+	extraResponseID := gjson.GetBytes(out, "messages.2.tool_call_id").String()
+
+	if firstResponseID != callID {
+		t.Fatalf("messages.1.tool_call_id = %q, want %q. Output: %s", firstResponseID, callID, string(out))
+	}
+	if !strings.HasPrefix(extraResponseID, "call_") {
+		t.Fatalf("extra response fallback tool_call_id = %q, want call_ prefix. Output: %s", extraResponseID, string(out))
+	}
+	if extraResponseID == callID {
+		t.Fatalf("extra response reused consumed tool_call_id %q. Output: %s", extraResponseID, string(out))
+	}
+}