Fix Gemini function-calling INVALID_ARGUMENT by relaxing Gemini tool validation and cleaning schema

internal/runtime/executor/antigravity_executor.go

@@ -1214,6 +1214,17 @@ func (e *AntigravityExecutor) buildRequest(ctx context.Context, auth *cliproxyau
 		// const->enum conversion, and flattening of types/anyOf.
 		strJSON = util.CleanJSONSchemaForAntigravity(strJSON)
 
+		payload = []byte(strJSON)
+	} else {
+		strJSON := string(payload)
+		paths := make([]string, 0)
+		util.Walk(gjson.Parse(strJSON), "", "parametersJsonSchema", &paths)
+		for _, p := range paths {
+			strJSON, _ = util.RenameKey(strJSON, p, p[:len(p)-len("parametersJsonSchema")]+"parameters")
+		}
+		// Clean tool schemas for Gemini to remove unsupported JSON Schema keywords
+		// without adding empty-schema placeholders.
+		strJSON = util.CleanJSONSchemaForGemini(strJSON)
 		payload = []byte(strJSON)
 	}
 
@@ -1405,7 +1416,13 @@ func geminiToAntigravity(modelName string, payload []byte, projectID string) []b
 	template, _ = sjson.Set(template, "request.sessionId", generateStableSessionID(payload))
 
 	template, _ = sjson.Delete(template, "request.safetySettings")
-	//	template, _ = sjson.Set(template, "request.toolConfig.functionCallingConfig.mode", "VALIDATED")
+	if toolConfig := gjson.Get(template, "toolConfig"); toolConfig.Exists() && !gjson.Get(template, "request.toolConfig").Exists() {
+		template, _ = sjson.SetRaw(template, "request.toolConfig", toolConfig.Raw)
+		template, _ = sjson.Delete(template, "toolConfig")
+	}
+	if strings.Contains(modelName, "claude") {
+		template, _ = sjson.Set(template, "request.toolConfig.functionCallingConfig.mode", "VALIDATED")
+	}
 
 	if strings.Contains(modelName, "claude") || strings.Contains(modelName, "gemini-3-pro-high") {
 		gjson.Get(template, "request.tools").ForEach(func(key, tool gjson.Result) bool {

internal/translator/gemini-cli/openai/chat-completions/gemini-cli_openai_request.go

@@ -249,7 +249,8 @@ func ConvertOpenAIRequestToGeminiCLI(modelName string, inputRawJSON []byte, _ bo
 						fid := tc.Get("id").String()
 						fname := tc.Get("function.name").String()
 						fargs := tc.Get("function.arguments").String()
-						node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".functionCall.name", fname)
+					node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".functionCall.id", fid)
+					node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".functionCall.name", fname)
 						node, _ = sjson.SetRawBytes(node, "parts."+itoa(p)+".functionCall.args", []byte(fargs))
 						node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".thoughtSignature", geminiCLIFunctionThoughtSignature)
 						p++
@@ -264,12 +265,13 @@ func ConvertOpenAIRequestToGeminiCLI(modelName string, inputRawJSON []byte, _ bo
 					pp := 0
 					for _, fid := range fIDs {
 						if name, ok := tcID2Name[fid]; ok {
-							toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.name", name)
+						toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.id", fid)
+						toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.name", name)
 							resp := toolResponses[fid]
 							if resp == "" {
 								resp = "{}"
 							}
-							toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.response.result", []byte(resp))
+						toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.response.output", []byte(resp))
 							pp++
 						}
 					}

internal/translator/gemini-cli/openai/chat-completions/gemini-cli_openai_response.go

@@ -149,7 +149,11 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 
 				functionCallTemplate := `{"id": "","index": 0,"type": "function","function": {"name": "","arguments": ""}}`
 				fcName := functionCallResult.Get("name").String()
-				functionCallTemplate, _ = sjson.Set(functionCallTemplate, "id", fmt.Sprintf("%s-%d-%d", fcName, time.Now().UnixNano(), atomic.AddUint64(&functionCallIDCounter, 1)))
+				fcID := functionCallResult.Get("id").String()
+				if fcID == "" {
+					fcID = fmt.Sprintf("%s-%d-%d", fcName, time.Now().UnixNano(), atomic.AddUint64(&functionCallIDCounter, 1))
+				}
+				functionCallTemplate, _ = sjson.Set(functionCallTemplate, "id", fcID)
 				functionCallTemplate, _ = sjson.Set(functionCallTemplate, "index", functionCallIndex)
 				functionCallTemplate, _ = sjson.Set(functionCallTemplate, "function.name", fcName)
 				if fcArgsResult := functionCallResult.Get("args"); fcArgsResult.Exists() {

internal/translator/gemini/gemini-cli/gemini_gemini-cli_request.go

@@ -46,19 +46,6 @@ func ConvertGeminiCLIRequestToGemini(_ string, inputRawJSON []byte, _ bool) []by
 		}
 	}
 
-	gjson.GetBytes(rawJSON, "contents").ForEach(func(key, content gjson.Result) bool {
-		if content.Get("role").String() == "model" {
-			content.Get("parts").ForEach(func(partKey, part gjson.Result) bool {
-				if part.Get("functionCall").Exists() {
-					rawJSON, _ = sjson.SetBytes(rawJSON, fmt.Sprintf("contents.%d.parts.%d.thoughtSignature", key.Int(), partKey.Int()), "skip_thought_signature_validator")
-				} else if part.Get("thoughtSignature").Exists() {
-					rawJSON, _ = sjson.SetBytes(rawJSON, fmt.Sprintf("contents.%d.parts.%d.thoughtSignature", key.Int(), partKey.Int()), "skip_thought_signature_validator")
-				}
-				return true
-			})
-		}
-		return true
-	})
 
 	return common.AttachDefaultSafetySettings(rawJSON, "safetySettings")
 }

internal/translator/gemini/openai/chat-completions/gemini_openai_request.go

@@ -255,7 +255,8 @@ func ConvertOpenAIRequestToGemini(modelName string, inputRawJSON []byte, _ bool)
 						fid := tc.Get("id").String()
 						fname := tc.Get("function.name").String()
 						fargs := tc.Get("function.arguments").String()
-						node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".functionCall.name", fname)
+					node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".functionCall.id", fid)
+					node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".functionCall.name", fname)
 						node, _ = sjson.SetRawBytes(node, "parts."+itoa(p)+".functionCall.args", []byte(fargs))
 						node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".thoughtSignature", geminiFunctionThoughtSignature)
 						p++
@@ -270,12 +271,13 @@ func ConvertOpenAIRequestToGemini(modelName string, inputRawJSON []byte, _ bool)
 					pp := 0
 					for _, fid := range fIDs {
 						if name, ok := tcID2Name[fid]; ok {
-							toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.name", name)
+						toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.id", fid)
+						toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.name", name)
 							resp := toolResponses[fid]
 							if resp == "" {
 								resp = "{}"
 							}
-							toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.response.result", []byte(resp))
+						toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.response.output", []byte(resp))
 							pp++
 						}
 					}

internal/translator/gemini/openai/chat-completions/gemini_openai_response.go

@@ -187,7 +187,11 @@ func ConvertGeminiResponseToOpenAI(_ context.Context, _ string, originalRequestR
 
 						functionCallTemplate := `{"id": "","index": 0,"type": "function","function": {"name": "","arguments": ""}}`
 						fcName := functionCallResult.Get("name").String()
-						functionCallTemplate, _ = sjson.Set(functionCallTemplate, "id", fmt.Sprintf("%s-%d-%d", fcName, time.Now().UnixNano(), atomic.AddUint64(&functionCallIDCounter, 1)))
+						fcID := functionCallResult.Get("id").String()
+						if fcID == "" {
+							fcID = fmt.Sprintf("%s-%d-%d", fcName, time.Now().UnixNano(), atomic.AddUint64(&functionCallIDCounter, 1))
+						}
+						functionCallTemplate, _ = sjson.Set(functionCallTemplate, "id", fcID)
 						functionCallTemplate, _ = sjson.Set(functionCallTemplate, "index", functionCallIndex)
 						functionCallTemplate, _ = sjson.Set(functionCallTemplate, "function.name", fcName)
 						if fcArgsResult := functionCallResult.Get("args"); fcArgsResult.Exists() {

internal/translator/gemini/openai/responses/gemini_openai-responses_request.go

@@ -290,11 +290,11 @@ func ConvertOpenAIResponsesRequestToGemini(modelName string, inputRawJSON []byte
 				// Set the raw JSON output directly (preserves string encoding)
 				if outputRaw != "" && outputRaw != "null" {
 					output := gjson.Parse(outputRaw)
-					if output.Type == gjson.JSON {
+				if output.Type == gjson.JSON {
-						functionResponse, _ = sjson.SetRaw(functionResponse, "functionResponse.response.result", output.Raw)
+					functionResponse, _ = sjson.SetRaw(functionResponse, "functionResponse.response.output", output.Raw)
-					} else {
+				} else {
-						functionResponse, _ = sjson.Set(functionResponse, "functionResponse.response.result", outputRaw)
+					functionResponse, _ = sjson.Set(functionResponse, "functionResponse.response.output", outputRaw)
-					}
+				}
 				}
 				functionContent, _ = sjson.SetRaw(functionContent, "parts.-1", functionResponse)
 				out, _ = sjson.SetRaw(out, "contents.-1", functionContent)

internal/util/gemini_schema.go

@@ -16,6 +16,93 @@ var gjsonPathKeyReplacer = strings.NewReplacer(".", "\\.", "*", "\\*", "?", "\\?
 // It handles unsupported keywords, type flattening, and schema simplification while preserving
 // semantic information as description hints.
 func CleanJSONSchemaForAntigravity(jsonStr string) string {
+	return cleanJSONSchema(jsonStr, true)
+}
+
+func removeKeywords(jsonStr string, keywords []string) string {
+	for _, key := range keywords {
+		for _, p := range findPaths(jsonStr, key) {
+			if isPropertyDefinition(trimSuffix(p, "."+key)) {
+				continue
+			}
+			jsonStr, _ = sjson.Delete(jsonStr, p)
+		}
+	}
+	return jsonStr
+}
+
+// removePlaceholderFields removes placeholder-only properties ("_" and "reason") and their required entries.
+func removePlaceholderFields(jsonStr string) string {
+	// Remove "_" placeholder properties.
+	paths := findPaths(jsonStr, "_")
+	sortByDepth(paths)
+	for _, p := range paths {
+		if !strings.HasSuffix(p, ".properties._") {
+			continue
+		}
+		jsonStr, _ = sjson.Delete(jsonStr, p)
+		parentPath := trimSuffix(p, ".properties._")
+		reqPath := joinPath(parentPath, "required")
+		req := gjson.Get(jsonStr, reqPath)
+		if req.IsArray() {
+			var filtered []string
+			for _, r := range req.Array() {
+				if r.String() != "_" {
+					filtered = append(filtered, r.String())
+				}
+			}
+			if len(filtered) == 0 {
+				jsonStr, _ = sjson.Delete(jsonStr, reqPath)
+			} else {
+				jsonStr, _ = sjson.Set(jsonStr, reqPath, filtered)
+			}
+		}
+	}
+
+	// Remove placeholder-only "reason" objects.
+	reasonPaths := findPaths(jsonStr, "reason")
+	sortByDepth(reasonPaths)
+	for _, p := range reasonPaths {
+		if !strings.HasSuffix(p, ".properties.reason") {
+			continue
+		}
+		parentPath := trimSuffix(p, ".properties.reason")
+		props := gjson.Get(jsonStr, joinPath(parentPath, "properties"))
+		if !props.IsObject() || len(props.Map()) != 1 {
+			continue
+		}
+		desc := gjson.Get(jsonStr, p+".description").String()
+		if desc != "Brief explanation of why you are calling this tool" {
+			continue
+		}
+		jsonStr, _ = sjson.Delete(jsonStr, p)
+		reqPath := joinPath(parentPath, "required")
+		req := gjson.Get(jsonStr, reqPath)
+		if req.IsArray() {
+			var filtered []string
+			for _, r := range req.Array() {
+				if r.String() != "reason" {
+					filtered = append(filtered, r.String())
+				}
+			}
+			if len(filtered) == 0 {
+				jsonStr, _ = sjson.Delete(jsonStr, reqPath)
+			} else {
+				jsonStr, _ = sjson.Set(jsonStr, reqPath, filtered)
+			}
+		}
+	}
+
+	return jsonStr
+}
+
+// CleanJSONSchemaForGemini transforms a JSON schema to be compatible with Gemini tool calling.
+// It removes unsupported keywords and simplifies schemas, without adding empty-schema placeholders.
+func CleanJSONSchemaForGemini(jsonStr string) string {
+	return cleanJSONSchema(jsonStr, false)
+}
+
+func cleanJSONSchema(jsonStr string, addPlaceholder bool) string {
 	// Phase 1: Convert and add hints
 	jsonStr = convertRefsToHints(jsonStr)
 	jsonStr = convertConstToEnum(jsonStr)
@@ -31,10 +118,16 @@ func CleanJSONSchemaForAntigravity(jsonStr string) string {
 
 	// Phase 3: Cleanup
 	jsonStr = removeUnsupportedKeywords(jsonStr)
+	if !addPlaceholder {
+		// Gemini schema cleanup: remove nullable/title and placeholder-only fields.
+		jsonStr = removeKeywords(jsonStr, []string{"nullable", "title"})
+		jsonStr = removePlaceholderFields(jsonStr)
+	}
 	jsonStr = cleanupRequiredFields(jsonStr)
-
 	// Phase 4: Add placeholder for empty object schemas (Claude VALIDATED mode requirement)
-	jsonStr = addEmptySchemaPlaceholder(jsonStr)
+	if addPlaceholder {
+		jsonStr = addEmptySchemaPlaceholder(jsonStr)
+	}
 
 	return jsonStr
 }