[Bug]: Clarify the name & usage of the X-A2A-Notification-Token header

[jmesnil]

What happened?

This HTTP Header is used in the Push Notification Setup and Usage section without much context.

From the example, it seems obvious that it corresponds to the configuration.pushNotificationConfig.token sent by the user with the message but it might be worth calling out.

I also wonder if this header should be named X-A2A-Notification-Token or A2A-Notification-Token.
I am working on updating the other HTTP headers names for the Java SDK (a2aproject/a2a-java#709) and it seem inconsistent that this one continues to use the X-.
Could you confirm if the current name is still correct? thanks

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[chorghemaruti64-creator]

The naming inconsistency is worth fixing for SDK interoperability, but there's a related concern worth raising: this token needs to be discoverable at registration time, not just per-call.

When an agent registers its push notification endpoint (e.g., in an Agent Card or capability manifest), including the expected notification token format/scheme as metadata would let callers pre-configure push correctly — before the first SendMessage.

For cross-org A2A where two agents that have never communicated find each other via a registry, the push notification setup should ideally be part of the 'capability handshake' at discovery time, not improvised at call time. The header naming becomes clearer if the spec also defines when and where this token originates in the agent lifecycle.

[darrelmiller]

That's an error. The specification does not define any headers that start with x-. It is not clear to me what this value does. Any credentials sent by the push notification should be sent in the Authorization header as defined by HTTP.