This Deliverable outlines a prototype of a spatially explicit interactive online tool (Deliverable D6.3) and outlines the objectives for the development of a methodological handbook on transdisciplinary sustainability assessment (Deliverable D6.4). The document provides an outline of the technical elements for the tool, based upon the web app development environment of Esri (Story Maps). These elements include the graphical user interface (GUI) and server side data management, and a set of variables to be implemented, derived from the description of Socio-Ecological Systems which describe the different dimensions of sustainability. These specifications lay the foundation for building a prototype version of the tool, the development and content of which continues until release of the tool at the end of the UNISECO project. The overall purpose of the tool is to increase understanding of the sustainability of agriculture, and in particular the role that agro-ecological transitions can play in increasing sustainability of European agriculture. For this purpose the tool provides a channel for delivering and viewing information as an effective means of communication between actors involved in such transitions. The plans for development of the tools are to implement it on a platform which requires minimal technical knowledge for easy content creation at a local level, for example by other projects or farmers who want to share information on more sustainable practices in agriculture. The tool is based upon the use of maps of different aspects of sustainability of farming systems, available at different spatial resolutions. Maps provide interactive visual representations of the geography of an area (Tomlinson, 2013), to which stories of farmers and other value chain actors who aspire more sustainable solutions for food production can be associated. Maps also provide an output format for the communication of results of spatially distributed Decision Support Tools which can support illustrations of why some solutions work, and their limitations. The tool will include indicators of social, economic and environmental dimensions of sustainability. The qualitative data collected will be used in stories developed about the project case studies, and quantitative data will be presented as maps created from statistical data and model outputs. The concept of the tool was discussed in workshops with stakeholders and members of the EU Multi-Actor Platform. Their feedback has informed the development of plans for the tool, including the inclusion of indicators such as biodiversity and pesticide use, which would be important considerations when communicating information on sustainability of agro-ecological farming. Other items highlighted in the feedback included the benefits of using audio-visual video material as part of stories of agro-ecological farms. It is proposed that the tool will be managed by a key stakeholder (WWF) to enable knowledge sharing after the completion of the UNISECO project.