Introduction Appraisal of Guidelines for Research and Evaluation (AGREE II) is an instrument that informs development, reporting and assessment of clinical practice guidelines. Previous research has demonstrated the need for improvement in methodological and reporting quality of clinical practice guidelines specifically in surgery. We aimed to develop an AGREE II extension document for application in surgical guidelines. Methods and analysis We have performed a structured literature review and assessment of guidelines in surgery using the AGREE II instrument. In exploratory analyses, we have identified factors associated with guideline quality. We have performed reliability and factor analyses to inform the development of an extension document. We will summarise this information and present it to a Delphi panel of stakeholders. We will perform iterative Delphi rounds and we will summarise the final results to develop the extension instrument in a dedicated consensus conference. Ethics and dissemination Funding bodies will not be involved in the development of the instrument. Research ethics committee and Health Research Authority approval was waived, since this is a professional staff study only and no duty of care lies with the National Health Service to any of the participants. Conflicts of interest, if any, will be addressed by reassigning functions or replacing participants with relevant conflicts. The results will be disseminated through publication in peer reviewed journals, the funders’ websites, social media and direct contact with guideline development organisations and peer-reviewed journals that publish guidelines.