ERC-8004: Agent Trust Protocol

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Key Features

• Identity Registry: Portable agent identifiers based on ERC-721 NFTs
• Reputation Registry: Standardized feedback and rating system for agents
• Validation Registry: Independent verification hooks where third-party validators can attest to agent outputs—supporting stake-secured re-execution, zkML proofs, or TEE attestations for high-stakes operations
• Cross-Chain Support: Works on any EVM-compatible chain including Celo

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Why ERC-8004?

• Discovery: How do agents find each other? The Identity Registry provides searchable metadata—agents query the registry to discover other agents by capabilities, endpoints, or domain.
• Identity: How do agents verify who they’re dealing with? Each agent is an ERC-721 NFT with a cryptographically linked wallet, enabling verification that you’re communicating with the authentic agent owner.
• Trust: How do agents evaluate reliability? The Reputation Registry stores feedback from every interaction, creating a portable track record that travels with the agent across platforms.

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Protocol stack

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The Three Registries

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1. Identity Registry

• Every agent identity is represented as an ERC-721 NFT—the agent itself runs off-chain, but its on-chain identity is an NFT that’s browsable in wallets, transferable between owners, and queryable by smart contracts
• agentURI points to registration file with endpoints
• Supports multiple endpoint types (A2A, MCP, wallet, ENS, DIDs)
• Domain verification for endpoint ownership

{
  "type": "Agent",
  "name": "My AI Agent",
  "description": "Description of capabilities",
  "image": "ipfs://...",
  "endpoints": [
    {
      "type": "a2a",
      "url": "https://example.com/.well-known/agent.json"
    },
    {
      "type": "mcp",
      "url": "https://example.com/mcp"
    },
    {
      "type": "wallet",
      "address": "0x...",
      "chainId": 42220
    }
  ],
  "supportedTrust": ["reputation", "validation", "tee"]
}

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2. Reputation Registry

• giveFeedback() - Submit feedback with score and tags
• revokeFeedback() - Remove previous feedback
• readAllFeedback() - Get all feedback for an agent
• getSummary() - Get aggregated reputation summary

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3. Validation Registry

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Contract Deployments

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Celo Mainnet

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Celo Sepolia (Testnet)

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Quick Start

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Install SDK

# JavaScript/TypeScript
npm install @chaoschain/sdk

# Python
pip install chaoschain-sdk

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Register an Agent

1. Create a registration file (JSON) describing your agent’s name, capabilities, and endpoints
2. Upload it to IPFS or host it at a public URL
3. Call the registry to mint your agent NFT with the URI pointing to that file

import { IdentityRegistry } from '@chaoschain/sdk';

const registry = new IdentityRegistry(provider);

// Upload registration file to IPFS first
const agentURI = 'ipfs://QmYourRegistrationFile';

// Register and get agent ID
const tx = await registry.register(agentURI);
const agentId = tx.events.Transfer.returnValues.tokenId;

console.log('Agent registered with ID:', agentId);

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Give Feedback

import { ReputationRegistry } from '@chaoschain/sdk';

const reputation = new ReputationRegistry(provider);

await reputation.giveFeedback(
  agentId,
  85,                    // score (0-100)
  0,                     // decimals
  'starred',             // tag1: category
  '',                    // tag2: optional
  'https://agent.example.com',  // endpoint used
  'ipfs://QmDetailedFeedback',  // detailed feedback URI
  feedbackHash           // keccak256 of feedback content
);

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Query Agent Reputation

// Get all feedback
const feedback = await reputation.readAllFeedback(agentId);

// Get summary statistics
const summary = await reputation.getSummary(agentId);
console.log('Average rating:', summary.averageScore);
console.log('Total reviews:', summary.totalFeedback);

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Use Cases

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DeFi Trading Agents

1. Queries the Identity Registry to discover available strategy agents
2. Filters candidates using the Reputation Registry (checking track records, success rates)
3. Selects an agent and requests a trade
4. Pays for the service via x402 (HTTP-native payments)
5. After the trade completes, submits feedback to build the strategy agent’s reputation

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Multi-Agent Workflows

• Discover each other via Identity Registry
• Verify credentials before delegation
• Track performance with Reputation Registry
• Use Validation Registry for high-stakes decisions

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Integration with Celo

• Fee abstraction: Register agents and give feedback paying gas in stablecoins
• x402 payments: Combine trust verification with instant payments
• MCP servers: Agents can expose capabilities via Celo MCP Server

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Resources

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Related Protocols

• x402 - Payment layer for AI agents
• Agent Skills - Modular agent capabilities
• MCP Servers - Connect agents to data and tools