Some of the key features of agile development are,

• Collective code ownership and freedom to change.

• Incremental approach (e.g. user stories are incrementally implemented). Automation (e.g. TDD -- Test Driven Development).

• Customer focused (for e.g. internal and external users and business analysts are your immediate customers).

• Design must be simple.

• Designing is an ongoing activity with constant re-factoring to achieve the rules of code simplicity like no duplication, verified by automated tests, separation of responsibilities, and minimum number of classes, methods, and lines.