Agent endpoint

An agent endpoint is the network address where an agent accepts protocol requests, such as the URL a client sends A2A JSON-RPC calls to.

In A2A v1.0. Endpoints are listed in the Agent Card’s supportedInterfaces array. Each AgentInterface entry has three required fields: a url, a protocolBinding (the core values are JSONRPC, GRPC and HTTP+JSON) and a protocolVersion. An optional tenant value routes requests when several agents share one endpoint. For HTTP-based bindings the URL must be an absolute HTTPS URL in production; for gRPC it is a hostname:port address. Emissar’s own published card lists one endpoint:

{
  "supportedInterfaces": [
    {"url": "https://emissar.ai/a2a/v1", "protocolBinding": "JSONRPC", "protocolVersion": "1.0"}
  ]
}

Choosing among endpoints. The array is in preference order, and the first entry is the provider’s preferred interface. A client takes the first entry whose binding it supports, uses that entry’s URL, and, if the entry sets tenant, sends exactly that value in every request.

Card URL and endpoint URL. They are separate. The Agent Card usually lives at a well-known URI on the provider’s domain, while the endpoint can sit at any path or on another host. The same URL may serve several bindings. In A2A v0.3 the endpoint was a top-level url with a preferredTransport field; v1.0 moved it into supportedInterfaces.

Checks. Production A2A traffic must be encrypted: HTTPS for HTTP-based bindings, TLS for gRPC. A client should validate the endpoint’s certificate, and note that the card’s serving domain and any card signatures are what vouch for an endpoint on another host. The Agent Card validator checks each supportedInterfaces entry and flags interface URLs that are not HTTPS.

Neighbouring terms. A remote agent is the server behind an endpoint. A resolver returns an endpoint when a client starts from something other than a domain.