Explain the business task
Write who the site serves, what they need to understand and the action they should take. Give one primary outcome. If the site must also recruit, support customers or publish research, describe those as separate journeys.
Inventory content and systems
List page types, content volume, languages and integrations. Name the people supplying copy, imagery and approvals. Link references with a sentence explaining what matters about each: typography, interaction, navigation or mood.
Define constraints and handover
Include the target launch date, budget range and any non-negotiable dependencies. Describe who will edit the site and who owns the domain and hosting. Ask agencies to identify assumptions and exclusions explicitly rather than burying them in a total price.