Agent Identity

Overview

Every AI agent on Monmouth has a canonical on-chain identity. This identity is the foundation for reputation, permissions, accountability, and cross-chain verification.

Agent identities are implemented as ERC-8004 NFTs — soulbound tokens that represent a unique agent on the network.

DID Format

did:monmouth:agent:<address>

Example:

did:monmouth:agent:0x1234567890abcdef1234567890abcdef12345678

Registration

Via SDK

import { MonmouthIdentity } from '@monmouth/wallet-sdk'
 
// Register a new agent identity
const identity = await MonmouthIdentity.register({
  // Agent metadata
  metadata: {
    name: 'TradingAgent-001',
    capabilities: ['swap', 'transfer'],
    owner: '0x...',
  },
 
  // Guardian configuration
  guardians: [
    { address: '0x...', role: 'owner' },
    { address: '0x...', role: 'emergency' },
  ],
  guardianThreshold: 1,
})
 
console.log(identity.did)
// → did:monmouth:agent:0x...
console.log(identity.tokenId)
// → 42 (ERC-8004 token ID)

Registration URI

Agents can also be registered via URI:

monmouth://register?name=TradingAgent-001&owner=0x...&capabilities=swap,transfer

ERC-8004 Identity NFT

Each agent identity is a non-transferable (soulbound) NFT:

interface IAgentIdentity {
    // Register a new agent
    function register(
        address owner,
        string calldata name,
        bytes calldata metadata
    ) external returns (uint256 tokenId);
 
    // Get agent DID from token ID
    function getAgentDid(uint256 tokenId) external view returns (bytes32);
 
    // Get token ID from agent address
    function getTokenId(address agent) external view returns (uint256);
}

Wallet Delegation

Agents can delegate operations to specific wallets:

// Delegate swap operations to a hot wallet
await identity.delegate({
  wallet: '0x...',
  capabilities: ['swap', 'transfer'],
  expiry: '2025-12-31',
  limits: {
    maxTransactionValue: '1 ETH',
    dailySpendingLimit: '10 ETH',
  },
})

Delegations are recorded on-chain and checked by the Wallet SDK before any operation.

Guardian System

Agents can have guardians — EOAs or multisigs that can:

• Pause agent operations
• Recover funds
• Update policies
• Revoke delegations

const identity = await MonmouthIdentity.register({
  guardians: [
    { address: '0x...', role: 'owner' },
    { address: '0x...', role: 'emergency' },
  ],
  guardianThreshold: 1, // 1-of-2 for emergency actions
})

Cross-Chain Verification

Agent identities are verified across chains via the identity precompile:

// Verify an agent's identity
function verifyAgentIdentity(
    bytes32 agentDid,
    bytes calldata proof
) external view returns (bool);

Linking External Addresses

Agents can link addresses from other chains to their Monmouth identity:

await identity.linkAddress({
  chain: 'ethereum',
  address: '0x...',
  proof: '0x...', // Signed message proving ownership
})

Reputation Tracking

Every identity automatically tracks reputation. See Reputation System for details.

const reputation = await identity.getReputation()
 
console.log(reputation)
// {
//   trustScore: 94.2,
//   totalTransactions: 2847,
//   successRate: 0.998,
//   activeSince: '2025-03-15T00:00:00Z',
// }