Verdict
A strong bridge between discovery and implementation. It expresses a change as independently testable capabilities, making large requests easier to review, sequence, and hand to agents without turning the specification into implementation trivia.
Best for
New features and significant changes that cross multiple modules or require agreement before engineering begins.
Keep in mind
A specification can still encode the wrong product choice, and the process is unnecessary for tiny changes whose behavior is already explicit.
Example task
Create a capability-oriented specification for organization-level API keys, covering issuance, scopes, rotation, audit, and revocation.