ERC-8004: Trustless Agents

ERC-8004 is a Draft EIP for discovering, choosing, and interacting with AI agents across organizational boundaries without pre-existing trust. It defines three on-chain registries deployed as per-chain singletons on any EVM chain.

Authors: Marco De Rossi (MetaMask), Davide Crapis (EF), Jordan Ellis (Google), Erik Reppel (Coinbase)

Full spec: references/spec.md

When to Use This Skill

• Registering AI agents on-chain (ERC-721 identity)
• Building or querying agent reputation/feedback systems
• Searching and discovering agents by capabilities, trust models, or endpoints
• Working with the Agent0 TypeScript SDK (agent0-sdk)
• Implementing ERC-8004 smart contract integrations
• Setting up agent wallets, MCP/A2A endpoints, or OASF taxonomies

Core Architecture

Three lightweight registries, each deployed as a UUPS-upgradeable singleton:

Registry	Purpose	Contract
Identity	ERC-721 NFTs for agent identities + registration files	IdentityRegistryUpgradeable
Reputation	Signed fixed-point feedback signals + off-chain detail files	ReputationRegistryUpgradeable
Validation	Third-party validator attestations (stake, zkML, TEE)	ValidationRegistryUpgradeable

Agent identity = agentRegistry (string eip155:{chainId}:{contractAddress}) + agentId (ERC-721 tokenId).

Each agent's agentURI points to a JSON registration file (IPFS or HTTPS) advertising name, description, endpoints (MCP, A2A, ENS, DID, wallet), OASF skills/domains, trust models, and x402 support.

See: references/contracts.md for full contract interfaces and addresses.

Quick Start with Agent0 SDK (TypeScript)

npm install agent0-sdk

Register an Agent

import { SDK } from 'agent0-sdk';

const sdk = new SDK({
  chainId: 84532,  // Base Sepolia
  rpcUrl: process.env.RPC_URL,
  privateKey: process.env.PRIVATE_KEY,
  ipfs: 'pinata',
  pinataJwt: process.env.PINATA_JWT,
});

const agent = sdk.createAgent(
  'MyAgent',
  'An AI agent that analyzes crypto markets',
  'https://example.com/agent-image.png'
);

// Configure endpoints and capabilities
await agent.setMCP('https://mcp.example.com', '2025-06-18', true);  // auto-fetches tools
await agent.setA2A('https://example.com/.well-known/agent-card.json', '0.3.0', true);
agent.setENS('myagent.eth');
agent.setActive(true);
agent.setX402Support(true);
agent.setTrust(true, false, false);  // reputation only

// Add OASF taxonomy
agent.addSkill('natural_language_processing/natural_language_generation/summarization', true);
agent.addDomain('finance_and_business/investment_services', true);

// Register on-chain (mints NFT + uploads to IPFS)
const tx = await agent.registerIPFS();
const { result } = await tx.waitConfirmed();
console.log(`Registered: ${result.agentId}`);  // e.g. "84532:42"

Search for Agents

const sdk = new SDK({ chainId: 84532, rpcUrl: process.env.RPC_URL });

// Search by capabilities
const agents = await sdk.searchAgents({
  hasMCP: true,
  active: true,
  x402support: true,
  mcpTools: ['financial_analyzer'],
  supportedTrust: ['reputation'],
});

// Get a specific agent
const agent = await sdk.getAgent('84532:42');

// Semantic search
const results = await sdk.searchAgents(
  { keyword: 'crypto market analysis' },
  { sort: ['semanticScore:desc'] }
);

Give Feedback

// Prepare optional off-chain feedback file
const feedbackFile = await sdk.prepareFeedbackFile({
  text: 'Accurate market analysis',
  capability: 'tools',
  name: 'financial_analyzer',
  proofOfPayment: { txHash: '0x...', chainId: '8453', fromAddress: '0x...', toAddress: '0x...' },
});

// Submit feedback (value=85 out of 100)
const tx = await sdk.giveFeedback('84532:42', 85, 'starred', '', '', feedbackFile);
await tx.waitConfirmed();

// Read reputation summary
const summary = await sdk.getReputationSummary('84532:42');
console.log(`Average: ${summary.averageValue}, Count: ${summary.count}`);

See: references/sdk-typescript.md for full SDK API reference.

Registration File Format

Every agent's agentURI resolves to this JSON structure:

{
  "type": "https://eips.ethereum.org/EIPS/eip-8004#registration-v1",
  "name": "MyAgent",
  "description": "What it does, pricing, interaction methods",
  "image": "https://example.com/agent.png",
  "services": [
    { "name": "MCP", "endpoint": "https://mcp.example.com", "version": "2025-06-18", "mcpTools": ["tool1"] },
    { "name": "A2A", "endpoint": "https://example.com/.well-known/agent-card.json", "version": "0.3.0" },
    { "name": "OASF", "endpoint": "https://github.com/agntcy/oasf/", "version": "v0.8.0",
      "skills": ["natural_language_processing/summarization"],
      "domains": ["finance_and_business/investment_services"] },
    { "name": "ENS", "endpoint": "myagent.eth", "version": "v1" },
    { "name": "agentWallet", "endpoint": "eip155:8453:0x..." }
  ],
  "registrations": [
    { "agentId": 42, "agentRegistry": "eip155:84532:0x8004A818BFB912233c491871b3d84c89A494BD9e" }
  ],
  "supportedTrust": ["reputation", "crypto-economic", "tee-attestation"],
  "active": true,
  "x402Support": true
}

The registrations field creates a bidirectional cryptographic link: the NFT points to this file, and this file points back to the NFT. This enables endpoint domain verification via /.well-known/agent-registration.json.

See: references/registration.md for best practices (Four Golden Rules) and complete field reference.

Contract Addresses

All registries deploy to deterministic vanity addresses via CREATE2 (SAFE Singleton Factory):

Mainnet (Ethereum, Base, Polygon, Arbitrum, Optimism, etc.)

Registry	Address
Identity	0x8004A169FB4a3325136EB29fA0ceB6D2e539a432
Reputation	0x8004BAa17C55a88189AE136b182e5fdA19dE9b63
Validation	0x8004Cb1BF31DAf7788923b405b754f57acEB4272

Testnet (Sepolia, Base Sepolia, etc.)

Registry	Address
Identity	0x8004A818BFB912233c491871b3d84c89A494BD9e
Reputation	0x8004B663056A597Dffe9eCcC1965A193B7388713
Validation	0x8004Cb1BF31DAf7788923b405b754f57acEB4272

Same proxy addresses on: Ethereum, Base, Arbitrum, Avalanche, Celo, Gnosis, Linea, Mantle, MegaETH, Optimism, Polygon, Scroll, Taiko, Monad, BSC + testnets.

Reputation System

Feedback uses signed fixed-point numbers: value (int128) + valueDecimals (uint8, 0-18).

tag1	Measures	Example	value	valueDecimals
starred	Quality 0-100	87/100	87	0
reachable	Endpoint up (binary)	true	1	0
uptime	Uptime %	99.77%	9977	2
successRate	Success %	89%	89	0
responseTime	Latency ms	560ms	560	0

Anti-Sybil: getSummary() requires a non-empty clientAddresses array (caller must supply trusted reviewer list). Self-feedback is rejected (agent owner/operators cannot submit feedback on their own agent).

See: references/reputation.md for full feedback system, off-chain file format, and aggregation details.

OASF Taxonomy (v0.8.0)

Open Agentic Schema Framework provides standardized skills (136) and domains (204) for agent classification.

Top-level skill categories: natural_language_processing, images_computer_vision, audio, analytical_skills, multi_modal, agent_orchestration, advanced_reasoning_planning, data_engineering, security_privacy, evaluation_monitoring, devops_mlops, governance_compliance, tool_interaction, retrieval_augmented_generation, tabular_text

Top-level domain categories: technology, finance_and_business, healthcare, legal, education, life_science, agriculture, energy, environmental_science, government, manufacturing, transportation, and more.

Use slash-separated paths: agent.addSkill('natural_language_processing/natural_language_generation/summarization', true).

Key Concepts

Term	Meaning
agentRegistry	eip155:{chainId}:{contractAddress} - globally unique registry identifier
agentId	ERC-721 tokenId - numeric on-chain identifier (format in SDK: "chainId:tokenId")
agentURI	URI (IPFS/HTTPS) pointing to agent registration file
agentWallet	Reserved on-chain metadata key for verified payment address (EIP-712/ERC-1271)
feedbackIndex	1-indexed counter of feedback a clientAddress has given to an agentId
supportedTrust	Array: "reputation", "crypto-economic", "tee-attestation"
x402Support	Boolean flag for Coinbase x402 HTTP payment protocol support
OASF	Open Agentic Schema Framework - standardized agent skills/domains taxonomy
MCP	Model Context Protocol - tools, prompts, resources, completions
A2A	Agent2Agent - authentication, skills via AgentCards, task orchestration

Reference Index

Reference	Content
spec.md	Complete ERC-8004 specification (EIP text)
contracts.md	Smart contract interfaces, storage layout, deployment
sdk-typescript.md	Agent0 TypeScript SDK full API
registration.md	Registration file format, Four Golden Rules, domain verification
reputation.md	Feedback system, off-chain files, value encoding, aggregation
search-discovery.md	Agent search, subgraph queries, multi-chain discovery
oasf-taxonomy.md	Complete OASF v0.8.0 taxonomy: all 136 skills and 204 domains with slugs

Official Resources

• EIP Discussion: https://ethereum-magicians.org/t/erc-8004-trustless-agents/25098
• Contracts: https://github.com/erc-8004/erc-8004-contracts
• Best Practices: https://github.com/erc-8004/best-practices
• SDK Docs: https://sdk.ag0.xyz
• SDK Docs Source: https://github.com/agent0lab/agent0-sdk-docs
• TypeScript SDK: https://github.com/agent0lab/agent0-ts
• Python SDK: https://github.com/agent0lab/agent0-py
• Subgraph: https://github.com/agent0lab/subgraph
• OASF: https://github.com/agntcy/oasf