diff --git a/backend/internal/pkg/antigravity/request_transformer.go b/backend/internal/pkg/antigravity/request_transformer.go
index e5ab8ece..e0b5b886 100644
--- a/backend/internal/pkg/antigravity/request_transformer.go
+++ b/backend/internal/pkg/antigravity/request_transformer.go
@@ -210,6 +210,9 @@ func buildParts(content json.RawMessage, toolIDToName map[string]string, allowDu
 				// Claude 模型需要有效 signature，跳过无 signature 的 thinking block
 				log.Printf("Warning: skipping thinking block without signature for Claude model")
 				continue
+			} else {
+				// Gemini 模型使用 dummy signature
+				part.ThoughtSignature = dummyThoughtSignature
 			}
 			parts = append(parts, part)
 
@@ -384,6 +387,12 @@ func buildTools(tools []ClaudeTool) []GeminiToolDeclaration {
 	// 普通工具
 	var funcDecls []GeminiFunctionDecl
 	for _, tool := range tools {
+		// 跳过无效工具名称
+		if tool.Name == "" {
+			log.Printf("Warning: skipping tool with empty name")
+			continue
+		}
+
 		var description string
 		var inputSchema map[string]any
 
@@ -401,6 +410,14 @@ func buildTools(tools []ClaudeTool) []GeminiToolDeclaration {
 		// 清理 JSON Schema
 		params := cleanJSONSchema(inputSchema)
 
+		// 为 nil schema 提供默认值
+		if params == nil {
+			params = map[string]any{
+				"type":       "OBJECT",
+				"properties": map[string]any{},
+			}
+		}
+
 		funcDecls = append(funcDecls, GeminiFunctionDecl{
 			Name:        tool.Name,
 			Description: description,
diff --git a/backend/internal/service/gemini_messages_compat_service.go b/backend/internal/service/gemini_messages_compat_service.go
index e55d798a..a0bf1b6a 100644
--- a/backend/internal/service/gemini_messages_compat_service.go
+++ b/backend/internal/service/gemini_messages_compat_service.go
@@ -2271,6 +2271,14 @@ func convertClaudeToolsToGeminiTools(tools any) []any {
 			continue
 		}
 
+		// 为 nil params 提供默认值
+		if params == nil {
+			params = map[string]any{
+				"type":       "object",
+				"properties": map[string]any{},
+			}
+		}
+
 		funcDecls = append(funcDecls, map[string]any{
 			"name":        name,
 			"description": desc,