Make the public function contract understandable and stable.
1. Input modeling
Use explicit fields with meaningful constraints. Define optional values and defaults rather than inferring them from a natural-language blob.
2. Result modeling
Return bounded domain results and distinguish no matches from execution failure. Avoid leaking implementation types or sensitive fields that the caller does not need.
3. Descriptions and versioning
Explain what the operation does and which side effects it has. Preserve compatible semantics or introduce a deliberate new contract when behavior changes.
Worked scenario
A task search returns titles, IDs and due dates, but no private internal notes unless the operation explicitly requires them.
Apply it
Design the schema for a bounded task search and test empty filters, long inputs and no results.
Check your understanding
A caller can understand the contract without knowing your internal repository classes. Explain the decision and show evidence from your implementation or design. If you cannot demonstrate it yet, revisit the relevant section before continuing.