ERC-8004

ERC-8004 is the Agent Identity Standard for Ethereum that enables discovering, choosing, and interacting with agents across organizational boundaries without pre-existing trust.

What is ERC-8004?

ERC-8004 provides a standard way to represent AI agent identities on Ethereum using three core registries:

• Identity Registry - ERC-721 NFTs for unique agent identities
• Reputation Registry - Feedback and reputation tracking
• Validation Registry - Third-party validator attestations

This enables permissionless agent discovery, censorship-resistant identity, and interoperable trust signals across platforms.

Specification

📖 Read the full ERC-8004 specification

Contracts

The official ERC-8004 contracts are maintained by the 8004 team:

🔗 ERC-8004 Contracts Repository

Testnet Contract Addresses

ETH Sepolia

• IdentityRegistry: 0x8004a6090Cd10A7288092483047B097295Fb8847
• ReputationRegistry: 0x8004B8FD1A363aa02fDC07635C0c5F94f6Af5B7E
• ValidationRegistry: 0x8004CB39f29c09145F24Ad9dDe2A108C1A2cdfC5

Base Sepolia

• IdentityRegistry: 0x8004AA63c570c570eBF15376c0dB199918BFe9Fb
• ReputationRegistry: 0x8004bd8daB57f14Ed299135749a5CB5c42d341BF
• ValidationRegistry: 0x8004C269D0A5647E51E121FeB226200ECE932d55

Contract Functions

Identity Registry

Registration Functions:

• register() → uint256 agentId
• register(string tokenUri) → uint256 agentId
• register(string tokenUri, MetadataEntry[] metadata) → uint256 agentId

Management Functions:

• setAgentUri(uint256 agentId, string newUri)
• setMetadata(uint256 agentId, string key, bytes value)
• getMetadata(uint256 agentId, string key) → bytes

ERC-721 Functions:

• approve(address to, uint256 tokenId)
• setApprovalForAll(address operator, bool approved)
• transferFrom(address from, address to, uint256 tokenId)
• safeTransferFrom(address from, address to, uint256 tokenId)
• safeTransferFrom(address from, address to, uint256 tokenId, bytes data)

View Functions:

• balanceOf(address owner) → uint256
• ownerOf(uint256 tokenId) → address
• getApproved(uint256 tokenId) → address
• isApprovedForAll(address owner, address operator) → bool
• tokenURI(uint256 tokenId) → string
• name() → string
• symbol() → string
• supportsInterface(bytes4 interfaceId) → bool

Admin Functions:

• owner() → address
• transferOwnership(address newOwner)
• renounceOwnership()
• upgradeToAndCall(address newImplementation, bytes data)

Reputation Registry

Feedback Functions:

• giveFeedback(uint256 agentId, uint8 score, bytes32 tag1, bytes32 tag2, string feedbackUri, bytes32 feedbackHash, bytes feedbackAuth)
• revokeFeedback(uint256 agentId, uint64 feedbackIndex)
• appendResponse(uint256 agentId, address clientAddress, uint64 feedbackIndex, string responseUri, bytes32 responseHash)

Query Functions:

• readFeedback(uint256 agentId, address clientAddress, uint64 index) → (uint8 score, bytes32 tag1, bytes32 tag2, bool isRevoked)
• readAllFeedback(uint256 agentId, address[] clientAddresses, bytes32 tag1, bytes32 tag2, bool includeRevoked) → (address[] clients, uint8[] scores, bytes32[] tag1s, bytes32[] tag2s, bool[] revokedStatuses)
• getSummary(uint256 agentId, address[] clientAddresses, bytes32 tag1, bytes32 tag2) → (uint64 count, uint8 averageScore)
• getClients(uint256 agentId) → address[]
• getLastIndex(uint256 agentId, address clientAddress) → uint64
• getResponseCount(uint256 agentId, address clientAddress, uint64 feedbackIndex, address[] responders) → uint64 count

Admin Functions:

• getIdentityRegistry() → address
• owner() → address
• transferOwnership(address newOwner)
• renounceOwnership()
• upgradeToAndCall(address newImplementation, bytes data)

Validation Registry

Validation Functions:

• validationRequest(address validatorAddress, uint256 agentId, string requestUri, bytes32 requestHash)
• validationResponse(bytes32 requestHash, uint8 response, string responseUri, bytes32 responseHash, bytes32 tag)

Query Functions:

• getValidationStatus(bytes32 requestHash) → (address validatorAddress, uint256 agentId, uint8 response, bytes32 responseHash, bytes32 tag, uint256 lastUpdate)
• getSummary(uint256 agentId, address[] validatorAddresses, bytes32 tag) → (uint64 count, uint8 avgResponse)
• getAgentValidations(uint256 agentId) → bytes32[]
• getValidatorRequests(address validatorAddress) → bytes32[]
• validations(bytes32) → (address validatorAddress, uint256 agentId, uint8 response, bytes32 responseHash, bytes32 tag, uint256 lastUpdate)

Admin Functions:

• getIdentityRegistry() → address
• owner() → address
• transferOwnership(address newOwner)
• renounceOwnership()
• upgradeToAndCall(address newImplementation, bytes data)

File Examples

Registration File

{
  "type": "https://eips.ethereum.org/EIPS/eip-8004#registration-v1",
  "name": "myAgentName",
  "description": "A natural language description of the Agent",
  "image": "https://example.com/agent-image.png",
  "endpoints": [
    {
      "name": "MCP",
      "endpoint": "https://api.example.com/mcp",
      "version": "2025-06-18",
      "mcpTools": [
        "data_analysis",
        "chart_generation",
        "report_creation"
      ],
      "mcpPrompts": [
        "prompt_1",
        "prompt_2",
        "prompt_3"
      ],
      "mcpResources": [
        "resource_1",
        "resource_2",
        "resource_3"
      ]
    },
    {
      "name": "A2A",
      "endpoint": "https://api.example.com/a2a",
      "version": "0.30",
      "a2aSkills": [
        "skill_1",
        "skill_2",
        "skill_3"
      ]
    },
    {
      "name": "ENS",
      "endpoint": "vitalik.eth",
      "version": "v1"
    },
    {
      "name": "DID",
      "endpoint": "did:method:foobar",
      "version": "v1"
    },
    {
      "name": "agentWallet",
      "endpoint": "eip155:1:0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb7"
    }
  ],
  "registrations": [
    {
      "agentId": 241,
      "agentRegistry": "eip155:11155111:0x8004a6090Cd10A7288092483047B097295Fb8847"
    }
  ],
  "supportedTrusts": [
    "reputation",
    "crypto-economic",
    "tee-attestation"
  ],
  "active": true,
  "x402support": true
}

Feedback File

{
  "agentRegistry": "eip155:1:{identityRegistry}",
  "agentId": 22,
  "clientAddress": "eip155:1:{clientAddress}",
  "createdAt": "2025-09-23T12:00:00Z",
  "feedbackAuth": "...",
  "score": 70,
  "tag1": "foo",
  "tag2": "bar",
  "skill": "as-defined-by-A2A",
  "context": "as-defined-by-A2A",
  "task": "as-defined-by-A2A",
  "capability": "tools",
  "name": "Put the name of the MCP tool you liked!",
  "proofOfPayment": {
    "fromAddress": "0x00...",
    "toAddress": "0x00...",
    "chainId": "1",
    "txHash": "0x00..."
  }
}

Next Steps

• Learn about Agent Configuration
• Explore Usage Examples