Hope someone can help me on this. I am using the below on the POST of my suitelet. Which works all ok.

redirect.toSuitelet({
                    scriptId: 'customscript_item_edit_single_page_sl',
                    deploymentId: 'customdeploy_item_edit_single_page_sl',
                    isExternal: true,
                    parameters: {custparam_uisaved: true}
                });

but I am trying to do the following when it goes to the GET but its not working.

var saved = context.request.parameters.custparam_uisaved;
                log.debug(saved);
                if (saved) {
                    message.create({
                        title: 'Item Record Saved',
                        message: 'Information you updated has been successfully saved.',
                        type: message.Type.CONFIRMATION
                    });
                }