What three design principles should guide writing Ansible automation?

• Complexity kills productivity: keep automation simple.
• Optimise for readability: well-written playbooks document the workflow.
• Think declaratively: describe the desired state, not a sequence of commands.

1. Complexity kills productivity. Simpler is better. Ansible's tools are designed to be easy to use and its automation easy to write and read, so aim for simplicity in your own playbooks too. Clever tricks make automation hard for the next person to change.
2. Optimise for readability. The language is simple, declarative, text-based files. Written properly, a playbook clearly documents your workflow, so others can review it.
3. Think declaratively. Ansible is a desired-state engine: you state how systems should be, and Ansible changes only what is necessary to get there.

Go deeper:

• Good Practices for Ansible (Red Hat Communities of Practice) — the guide behind "complexity kills productivity", "readability counts" and "declarative over imperative".
• General tips (official docs) — "keep it simple" and readability advice for playbooks.