> ## Documentation Index
> Fetch the complete documentation index at: https://docs.polygon.technology/llms.txt
> Use this file to discover all available pages before exploring further.

# ERC-8004 on Polygon

> Reference and explanation for ERC-8004: onchain Identity, Reputation, and Validation registries for autonomous agents.

**ERC-8004** defines a lightweight, onchain trust layer for autonomous agents
using three registries: **Identity**, **Reputation**, and **Validation**.
The standard is designed to work alongside existing agent protocols (A2A, MCP).
Payments are out of scope for ERC-8004; however, payment proofs (e.g., from **x402**) can be
referenced in reputation data.

This page covers what ERC-8004 standardizes, how it relates to A2A, MCP, and
x402, and where to find the Polygon mainnet and Amoy deployments.

## Why ERC-8004?

Modern agent stacks focus on communication and capability exposure, not on open
discovery and trust across organizational boundaries. Google's **A2A** provides
agent authentication, capability advertisement via Agent Cards, and
orchestration, but does not standardize reputation or validation.
Anthropic's **MCP** connects LLM apps to external tools and data, and similarly
leaves trust and discovery to individual applications.

ERC-8004 adds the missing piece: standard onchain registries that any chain
can host as singletons. It links agents to MCP/A2A endpoints through an onchain
identity, with optional trust signals.

***

## What ERC-8004 standardizes (at a glance)

* **Identity Registry** - an **ERC-721 + URIStorage** registry that mints an
  *Agent ID* (`agentId`) and points its `tokenURI` to a JSON registration file
  (e.g., on IPFS/HTTPS) listing A2A/MCP endpoints, DIDs, ENS, wallets, etc.
  Ownership of the NFT = ownership of the agent entry.
* **Reputation Registry** - an interface for clients to submit **feedback**
  (score `0-100`, optional tags, and an optional off-chain file/URI + hash).
  Off-chain files may include **payment proofs** to correlate economics with
  feedback.
* **Validation Registry** - a request/response log for **independent
  validators** (e.g., stake-based re-execution, zkML verifiers, TEEs) to post
  attestations about an agent's work. Results can be queried onchain.

<Note title="Orthogonality">
  Payments are **orthogonal** to
  ERC-8004; the spec shows how **x402** proofs can be referenced in reputation
  data but does not dictate any settlement flow.
</Note>

## Polygon Deployments

ERC-8004 registries are deployed on **Polygon mainnet** and **Polygon Amoy**.

### Polygon Mainnet

* **IdentityRegistry:** [0x8004A169FB4a3325136EB29fA0ceB6D2e539a432](https://polygonscan.com/address/0x8004A169FB4a3325136EB29fA0ceB6D2e539a432)
* **ReputationRegistry:** [0x8004BAa17C55a88189AE136b182e5fdA19dE9b63](https://polygonscan.com/address/0x8004BAa17C55a88189AE136b182e5fdA19dE9b63)

### Amoy

* **IdentityRegistry:** [0x8004ad19E14B9e0654f73353e8a0B600D46C2898](https://amoy.polygonscan.com/address/0x8004ad19E14B9e0654f73353e8a0B600D46C2898)
* **ReputationRegistry:** [0x8004B12F4C2B42d00c46479e859C92e39044C930](https://amoy.polygonscan.com/address/0x8004B12F4C2B42d00c46479e859C92e39044C930)
* **ValidationRegistry:** [0x8004C11C213ff7BaD36489bcBDF947ba5eee289B](https://amoy.polygonscan.com/address/0x8004C11C213ff7BaD36489bcBDF947ba5eee289B)

***

## Read-Only Examples

The snippets below use `viem` to query the Amoy contracts. They are
deterministic and read-only, and work before any agents are minted. Note that
`tokenURI` and `ownerOf` only resolve for existing `agentId` values.

```ts theme={null}
import { createPublicClient, http } from "viem";
import { polygonAmoy } from "viem/chains";
import "dotenv/config";

const IDENTITY = "0x8004ad19E14B9e0654f73353e8a0B600D46C2898" as const;
const REPUTATION = "0x8004B12F4C2B42d00c46479e859C92e39044C930" as const;
const VALIDATION = "0x8004C11C213ff7BaD36489bcBDF947ba5eee289B" as const;

const erc721View = [
  { type: "function", name: "name", stateMutability: "view", inputs: [], outputs: [{ type:"string" }] },
  { type: "function", name: "symbol", stateMutability: "view", inputs: [], outputs: [{ type:"string" }] },
  { type: "function", name: "tokenURI", stateMutability: "view", inputs: [{ type:"uint256" }], outputs: [{ type:"string" }] },
];

const validationView = [
  { type:"function", name:"getValidationStatus", stateMutability:"view",
    inputs:[{type:"bytes32"}],
    outputs:[{type:"address"},{type:"uint256"},{type:"uint8"},{type:"bytes32"},{type:"uint256"}] },
];

async function main() {
  const pub = createPublicClient({ chain: polygonAmoy, transport: http() });

  // Identity registry metadata
  const name = await pub.readContract({ address: IDENTITY, abi: erc721View, functionName: "name" });
  const symbol = await pub.readContract({ address: IDENTITY, abi: erc721View, functionName: "symbol" });
  console.log({ name, symbol }); // e.g., "Agent Identity", "AGNT"

  // Sample agentId=1 (will throw if not yet minted)
  // const uri = await pub.readContract({ address: IDENTITY, abi: erc721View, functionName: "tokenURI", args:[1n] });
  // console.log({ uri });

  // Check a validation status by requestHash (bytes32)
  // const reqHash = "0x" + "00".repeat(32) as `0x${string}`;
  // const status = await pub.readContract({ address: VALIDATION, abi: validationView, functionName: "getValidationStatus", args:[reqHash] });
  // console.log({ status });
}
main();
```

### Where these come from in the spec

* Identity uses ERC-721 + URIStorage (hence tokenURI and ownership semantics).
* Validation exposes getValidationStatus/getSummary to query results.

<Note title="Future proofing and backwards compatibility">
  You can use more
  [modern interfaces and standards backwards compatible with ERC-721](https://eips.ethereum.org/EIPS/eip-6220)
  to access the same values if you wish.
</Note>

### How ERC-8004 Relates to A2A, MCP, and x402

A2A is the coordination layer (authentication, agent cards, lifecycle). ERC-8004
adds discovery and trust so agents from different organizations can find and
assess each other.

MCP is the tool/data layer. The ERC-8004 Identity record can link to MCP
endpoints, allowing agent wallets or marketplaces to enumerate capabilities
consistently.

x402 is the payment layer. ERC-8004 is payment-agnostic. You can optionally
embed payment proofs (such as x402 transaction hashes) in off-chain feedback
files referenced by the Reputation registry.

## Design Goals and Current Status

ERC-8004 is a Standards Track ERC proposal created August 13, 2025, currently
under public review.

The standard introduces pluggable trust models (reputation, crypto-economic
validation, zk/TEE attestations) with security proportional to the value at
risk. The registries are designed to be per-chain singletons for
straightforward discovery.

Active discussion topics include: handling onchain vs. off-chain data,
encouraging multiple independent reputation providers, and keeping payments
decoupled while allowing payment proofs to be referenced.

Development discussion takes place in the [ERC-8004 Builders](https://t.me/ERC8004)
Telegram group and the
[Ethereum Magicians forum thread](https://ethereum-magicians.org/t/erc-8004-trustless-agents/25098).