Protocol grammar

Authored once per protocol, not once per instance. The negative grammar travels with it: what a protocol vocabulary must not be read to mean is a property of the protocol, not of each network that speaks it.

display_name

ActivityPub

identity_scheme

https actor URI, discovered from acct: via WebFinger

traversal

actor -> outbox -> collection pages -> objects; actor -> followers/following for topology

cannot_infer

follows -> friend; follows -> trusted; a boosted post -> endorsement; an actor on a server -> membership of the institution running it; a public collection -> permission to republish; server software version -> governance

display_name

Model Context Protocol

identity_scheme

server base URL; resources addressed by URI within it

traversal

registry -> server -> resources/tools/prompts -> downstream systems

cannot_infer

an advertised tool -> authority to invoke it; a listed server -> an audited one; a resource URI -> a licence to redistribute what it returns; server availability -> the availability of what it fronts

display_name

Agent to Agent

identity_scheme

agent card at /.well-known/agent.json on the agent's origin

traversal

agent -> skills -> providers -> downstream agents

cannot_infer

a declared skill -> a skill that will perform; a card -> a priced or willing counterparty; delegation named in a card -> a contract between the parties; reachability -> authorization

display_name

Beckn

identity_scheme

participant subscriber id within a network registry

traversal

network -> participants -> catalogs -> fulfillment networks

cannot_infer

a listed participant -> a settled counterparty; a catalog entry -> available stock; a quoted price -> a price this institution will honour; network membership -> an admitted provider