The focus of the first phase is to organize the project.
Prior to appointing the project manager the executive leadership may have worked directly with an analyst and/or architect to develop an idea and draft a business case. Once the draft business case convincingly indicates that investing further in the idea is likely to be worthwhile will the executive leadership organize a steering committee and appoint a project manager.
Regardless of how the project comes to life, once appointed the project manager immediately develops the initial iteration plan. The office management function provides tools and working space for the emerging project team.
The project manager often need to adhere to the organization’s project governance body, which might want to review and approve the project plan and receive iteration reports.
The solution architect might need to adhere to architecture governance body, possibly in the form of an enterprise architecture function, which dictates the use of certain technologies and design principles. An architecture governance might also include an architecture board, which needs to review and approve the solution architecture document in certain phases.
The initial iteration plan defines tasks to write the project plan, a glossary and critical parts of the solution architecture document.
Most project managers will need to enlist the help of a solution architect, business analyst and test manager to achieve the goals of the organize phase.
The solution architect will work with the business analyst to develop a glossary. The test manager will work with the solution architect to describe technologies and define a strategy for testing in the solution architecture document.
As for tools, I always recommend setting up a project environment using Jira and Confluence rather than writing in Word and keeping documents in SharePoint. I don’t recommend Jira because it’s a popular tool in Scrum and SAFe, but because it’s convenient to develop iteration plans in Jira and link between Jira and documentation in Confluence. Also, Jira is great for managing detailed development and testing tasks, and there are great add-ons specialized for test management as well.
The organize phase almost always only require a single iteration.
Create the initial iteration plan to detail who will be doing what in the iteration.
Most of this plan should be filled in from the beginning, but a few topics (like handover) might be completed in later phases.
Create the glossary from the very beginning.
Write the introduction, the design constraints and design principles.
Also start writing about design properties, development, testing and deployment.
Finish the phase with an iteration report that lists achievements and lessons learned.