diff --git a/internal/sys/sys.go b/internal/sys/sys.go
index 9447f42b..52551526 100644
--- a/internal/sys/sys.go
+++ b/internal/sys/sys.go
@@ -38,6 +38,10 @@ func (s *SysServer) HandleRequest(method string, params json.RawMessage) (interf
 			log.Printf("Failed to unmarshal tool call params: %v", err)
 			return nil, fmt.Errorf("invalid params: %w", err)
 		}
+		if callParams.Name == "" {
+			log.Printf("Tool call missing name field")
+			return nil, fmt.Errorf("invalid params: missing tool name")
+		}
 		log.Printf("Calling tool: name=%s", callParams.Name)
 		return s.callTool(callParams.Name, callParams.Arguments)
 	default:
diff --git a/internal/sys/sys_test.go b/internal/sys/sys_test.go
index dbf6305f..0a3c69fa 100644
--- a/internal/sys/sys_test.go
+++ b/internal/sys/sys_test.go
@@ -222,10 +222,6 @@ func TestHandleRequest_ToolsCall_UnknownTool(t *testing.T) {
 			name:     "unknown tool",
 			toolName: "unknown_tool",
 		},
-		{
-			name:     "empty tool name",
-			toolName: "",
-		},
 		{
 			name:     "misspelled tool",
 			toolName: "sys_initialize",