Background: A2A and ERC-8004

The A2A (Agent-to-Agent) framework is the first widely adopted effort to standardize how autonomous agents describe and call each other.

At its core is the Agent Card — a machine-readable JSON document containing:

Identity & Metadata — name, description, maintainer signature.
Capabilities & Endpoints — what the agent can do and how to invoke it (REST, gRPC, WebSocket, etc.).
Authentication & Pricing Info — how to access the service, optional cost hints.

A2A enables any User Agent (UA) to discover an Agent Card and invoke a Target Agent (TA) without human intervention.

However, A2A intentionally limits its scope:

It does not provide a global discovery index — agents must still be found manually or through closed directories.
It does not include a trust or reputation mechanism — there is no shared history of performance or reviews.
It does not define how to anchor or verify the authenticity of Agent Cards to prevent tampering.

To address verifiability, the Web3 ecosystem introduced ERC-8004 (Ethereum Agent Registry Standard).

ERC-8004 specifies how to:

Register agent metadata on-chain.
Anchor file URIs and their hashes to ensure immutability.
Emit standard events (Registered, Updated, Revoked) so anyone can audit changes.

This brings integrity and provenance but still leaves search, ranking, and reputation scoring out of scope.

Some extensions such as AP2 focus on agent-to-payment workflows (allowing an agent to request or execute payments).

While useful for monetization, AP2 does not solve the fundamental discovery and trust problem.

Other payment protocols (e.g., X402/X408) are even further from the search/reputation layer and are not a core part of Agent3’s mission.

Agent3 builds directly on A2A and ERC-8004:

The goal is to create the missing global discovery + reputation layer that A2A and ERC-8004 alone do not provide.

Last updated 27 days ago