ERC-8004: On-Chain AI Agent Identity

ERC-8004 is an open Ethereum standard for discovering, choosing, and interacting with AI agents across organizational boundaries without pre-existing trust. It was created by the Sperax team and is deployed across 12 chains.

Spec: https://eips.ethereum.org/EIPS/eip-8004

Why ERC-8004?

As AI agents proliferate, we need a way to:

• Discover agents across platforms (not locked in one vendor)
• Verify agent capabilities and track record
• Trust agents without knowing who built them
• Pay agents via standard protocols (x402, on-chain)

ERC-8004 solves this with three on-chain registries.

The Three Registries

1. Identity Registry (ERC-721 NFT)

Every agent gets an NFT identity: a unique, transferrable on-chain identity.

• Based on ERC-721 with URIStorage
• TokenURI points to a JSON registration file
• Owners can update metadata, transfer, or burn
• One NFT = one agent identity

2. Reputation Registry

A standard interface for posting and querying feedback signals about agents.

Signal	Measures	Scale
starred	Quality rating	0-100
reachable	Endpoint reachable	binary
uptime	Availability	percentage
successRate	Task completion rate	percentage
responseTime	Response latency	milliseconds
tradingYield	Trading return	signed percentage
revenues	Cumulative revenue	USD

Star ratings map to the 0-100 scale:

• 1★ = 20, 2★ = 40, 3★ = 60, 4★ = 80, 5★ = 100

3. Validation Registry

Independent validator attestations for agent capabilities:

• zkML proofs (zero-knowledge machine learning)
• TEE attestations (trusted execution environment)
• Staker validations (economic security)
• Custom validator contracts

Agent Registration

Registration File Format

{
  "type": "https://eips.ethereum.org/EIPS/eip-8004#registration-v1",
  "name": "My Trading Agent",
  "description": "Automated yield optimizer on Arbitrum",
  "image": "https://three.ws/avatars/thumbs/default.png",
  "services": [
    {
      "name": "MCP",
      "endpoint": "https://api.myagent.com/mcp",
      "version": "2025-06-18",
      "mcpTools": ["getQuote", "executeTrade"]
    },
    {
      "name": "A2A",
      "endpoint": "https://api.myagent.com/.well-known/agent-card.json",
      "version": "0.3.0",
      "a2aSkills": ["defi/yield_optimization"]
    },
    {
      "name": "ENS",
      "endpoint": "myagent.eth",
      "version": "v1"
    }
  ],
  "x402Support": true,
  "active": true
}

Service Types

Service	Purpose	Use When
MCP	Model Context Protocol	Agent exposes tools for other AI to call
A2A	Agent-to-Agent	Agent participates in multi-agent workflows
ENS	Ethereum Name Service	Human-readable agent address
DID	Decentralized Identifier	Cross-chain identity

Key Operations

Operation	Description
registerAgent	Mint an agent NFT with metadata
lookupAgent	Query agent details by token ID
searchAgents	Find agents by criteria
updateMetadata	Update agent's registration file
transferAgent	Transfer ownership to new address
getAgentReputation	Fetch reputation signals
submitFeedback	Post a reputation signal
addValidation	Add validator attestation
getValidations	Query validations for an agent
listAgents	List agents by owner

Supported Chains (12)

Chain	Networks
Ethereum	Mainnet, Sepolia
BNB Chain	Mainnet, Testnet
Arbitrum	Mainnet, Sepolia
Base	Mainnet, Sepolia
Optimism	Mainnet, Sepolia
Polygon	Mainnet, Amoy

All contracts use vanity addresses starting with 0x8004...

Best Practices

Registration

1. Always include a rich registration file with name, description, image, and services
2. Declare services explicitly: other agents need to know how to communicate
3. Keep metadata current: update when endpoints change
4. Use active flag: set "active": false when taking agent offline

Reputation

1. Encourage feedback: more signals = more trust
2. Monitor your scores: respond to quality issues
3. Use standard signal types: stick to the defined tags for interoperability
4. Trusted probers (infra watchtowers) should regularly publish uptime/reachability

Security

1. Validate callers: check msg.sender for sensitive operations
2. Rate-limit feedback: prevent spam signals
3. Verify validators: ensure validator contracts are trustworthy

Use Cases for OpenClaw Agents

Register Your OpenClaw Agent On-Chain

Give your agent a verifiable identity that works across platforms:

1. Deploy agent registration via ERC-8004
2. Advertise MCP endpoints so other agents can discover your tools
3. Build reputation over time as users interact

Discover & Interact With Other Agents

Use the ERC-8004 registries to:

1. Find specialized agents (e.g., "DeFi yield optimizer on Arbitrum")
2. Check reputation before trusting
3. Call via MCP or A2A protocols

Build Agent Marketplaces

ERC-8004 provides the infra layer for on-chain agent marketplaces:

• Identity (who is this agent?)
• Reputation (is it any good?)
• Validation (has it been audited?)
• Discovery (how do I find it?)

Related Resources

Resource	URL
ERC-8004 Spec	https://eips.ethereum.org/EIPS/eip-8004
Best Practices	https://github.com/sperax
Agent Creator UI	https://github.com/sperax
Demo Agent	https://github.com/sperax
Solidity Contracts	https://github.com/sperax
Subgraph	https://github.com/sperax
SperaxOS	https://chat.sperax.io