Erc8004 Agent Liveness MCP server

ERC-8004 Agent Liveness

Checks whether an agent registered in the real ERC-8004 "Trustless Agents" Identity Registry (Base mainnet -- both the payment and the registry read, see "Chain scope" below) is actually alive right now -- not just that it was registered once. NEXUS candidate #10 -- manual build, not FORGE-generated, same manual-Cloud-Run-asset pattern as candidates #3/#4/#6/#8/#9/#13/#16.

GET /.well-known/402index-verify.txt (402index claim verification file).

• POST /verify-registered-agent {"agentid": 3} -- $0.10/call.**
• MCP tool verifyregisteredagent at /mcp, same params -- currently free, see "Known limitations".
• GET /health, GET /.well-known/agent-card.json, GET /openapi.json (has x-payment-info),

What this is (and why registration alone isn't enough)

ERC-8004 is a real, live Ethereum standard for on-chain agent identity: an agent mints an ERC-721 token in an IdentityRegistry, whose tokenURI points to an off-chain registration file (JSON: name, description, declared endpoints, active flag, supported trust methods). It went live on Ethereum mainnet 2026-01-29, with reference deployments on Base mainnet and Base/Ethereum/Linea Sepolia testnets. Registration is a one-time on-chain action -- a real registered agent can go completely dark (process killed, domain expired, endpoint changed) while its on-chain record persists unchanged forever. This asset closes that gap: it resolves the real on-chain registration AND performs a real MCP initialize handshake against whatever endpoint the registration declares, right now, at call time -- the same liveness-vs-registration distinction agent-verification-api (candidate #3) already draws for domain-claimed identities, applied here to on-chain-registered ones.

Grounding (verified live this session, not assumed from any single source)

against https://sepolia.base.org before being trusted: IdentityRegistry (0x8004A818BFB912233c491871b3d84c89A494BD9e) and ReputationRegistry (0x8004B663056A597Dffe9eCcC1965A193B7388713) both have real, non-empty deployed bytecode.

• Contract addresses, initially from a third-party summary, verified independently via eth_getCode

live against 3 real registered agents (agentId 1-3) before being trusted for this asset:

• ABI, pulled from the reference implementation (github.com/erc-8004/erc-8004-contracts/abis), tested

All 3 of ERC-8004's real URI schemes confirmed working live, not just the one the spec's own examples show.

• Agent 1's tokenURI resolves to a data:application/json;base64,... URI.
• Agent 2's resolves to ipfs://bafkreiff....
• Agent 3's resolves to a real https://api.snack.money/agent/.../registration.json URL.

"clientAddresses required" otherwise). This asset calls getClients(agentId) first and only calls getSummary if that returns at least one address; agents with zero feedback correctly report feedback_count: 0 without an RPC error.

• getSummary requires a non-empty clientAddresses array -- confirmed live (reverts with

mapped to AGENTNOTFOUND, not a crash.

• agentId=999999 (a real nonexistent token) correctly reverts with a custom error, confirmed live --

MCP handshake engine: reused, not reimplemented

Per the task brief's explicit instruction, nexusvalidatepublicurl, nexusnoredirectmcphttpclient, and mcphandshakecheck are ported verbatim from manualassets/agent-verification-api/main.py (candidate #3) -- same SSRF pre-check, same no-redirect posture (the exact fix applied there after the 2026-08-22 security review found a redirect-based SSRF bypass), same bounded timeout. Not modified beyond the asset-name constant. This asset's own contribution is upstream of that: resolving an ERC-8004 registration file (3 URI schemes) and picking a real endpoint out of its endpoints array to hand to that engine.

Chain scope

Shortened. The full README is on GitHub.