In an Agile environment, the role of the Business Analyst (BA) includes working closely with the development team and business stakeholders to clarify and prioritize requirements. One of the critical tasks during this process is to estimate the effort required to deliver each requirement. This estimation is essential for planning the iterations or sprints in Agile development. The BA collaborates with other team members to assess the complexity and effort involved, ensuring that the team can commit to achievable goals within each timeboxed iteration. This role does not typically include approving changes, version control, or identifying all requirements at the outset, which are handled by other roles or processes in Agile.

Reference: Business Analysis.pdf, Chapter 10, Establishing the Requirements