agentgate

AgentGate: Concordium agent identity checks, x402 paid API, MCP server

AgentGate

Is this AI agent who it says it is? One call tells you.

AgentGate checks an AI agent against the Concordium Agent Registry (CIS-8004, ERC-8004 compatible) and answers: is it registered, Active (not revoked), and Verified by Concordium (its published Agent Card matches the hash committed on-chain)? Use it before your agent trusts, hires or pays another agent, or to keep anonymous scripts out of your x402 paid API.

30-second quickstart

1. Try it now (free, no wallet, no signup):

curl "https://agentgate.agentgate.workers.dev/v1/check-agent/preview?id=Mf22soLh1NuZYFgBK8iSs"
# {"id":"Mf22soLh1NuZYFgBK8iSs","network":"mainnet","found":true,"active":true,"verified":true,"cardHashMatches":true,...,"tier":"free"}

2. Give it to your agent as a tool (MCP). Remote, nothing to install:

{ "mcpServers": { "agentgate": { "type": "http", "url": "https://agentgate.agentgate.workers.dev/mcp" } } }

Or run it locally over stdio: npx -y -p concordium-agentgate agentgate-mcp (or Docker: docker build -t agentgate-mcp . && docker run -i --rm agentgate-mcp). Either way you get one tool, check_agent({ id, network }).

3. Pay per call for the full record (owner account, agent wallet, Agent Card URI, token id): GET https://agentgate.agentgate.workers.dev/v1/check-agent?id=<badge> costs $0.005 USDC on Base over x402 v2. Any x402 client works; see examples/x402-paid-call.mjs. It is listed in the x402 Bazaar (PayAI).

4. Use it in code:

import { createAgentGateClient } from 'concordium-agentgate/client'; // or from this repo: ./src/client.js
const agentgate = createAgentGateClient();            // free preview; pass { paidFetch } for the paid route
const r = await agentgate.verify('Mf22soLh1NuZYFgBK8iSs');
if (!r.verified) throw new Error('untrusted agent');

Framework tools ready to paste: LangChain/LangGraph, Vercel AI SDK, OpenAI Agents SDK, ElizaOS.

What's in the repo:

• Library (src/registry.js): checkAgent(badgeOrAccount, { network }), with pluggable providers.
• Express-style middleware (src/middleware.js): agentGate(). Mount it before x402 paymentMiddleware.
• MCP server (mcp/server.js): a check_agent tool for Claude, Cursor and other MCP clients.
• Static checker page (docs/): a single HTML file you can open locally or host anywhere. live at https://agentgate-source.pages.dev/agentgate/demo/ (guide: https://youraitools.co/guides/x402-agent-verification)
• Paid x402 API (service/): check_agent at $0.005 USDC per call on Base mainnet, using the official @x402/* packages and the PayAI facilitator, and listed in the x402 Bazaar (PayAI). Live: https://agentgate.agentgate.workers.dev/v1/check-agent?id=<badge or account>. See service/README.md.
• Tests and a runnable demo.

Status: v0.1, an MVP built for the Concordium Trusted Agents Hackathon (Encode Club). Independent project, not affiliated with Concordium.

Why

x402 lets any agent pay any API with no signup, which also means any anonymous script can call it. Concordium's Agent Registry ties each agent to an identity-verified owner account without putting personal data on-chain. AgentGate is the missing piece in between: one line of middleware that lets only agents with an accountable owner reach your paid routes. Unverified agents are rejected before they are asked to pay.

Quickstart

# just the package: npm install concordium-agentgate   (MCP server: npx -y -p concordium-agentgate agentgate-mcp)
# full source (tests, demo, service): https://agentgate-source.pages.dev/agentgate/
curl -LO https://agentgate-source.pages.dev/agentgate/agentgate.bundle && git clone agentgate.bundle agentgate && cd agentgate
npm install
npm test              # unit + integration tests (offline)
npm run demo          # offline demo: MockProvider + mock x402 paywall
npm run demo:live     # real Concordium mainnet registry lookups (payment step still mocked)
npm run check -- Mf22soLh1NuZYFgBK8iSs                         # CLI, mainnet
npm run check -- JyP9TtQC3HCNrTYR3sc2T --network testnet       # CLI, testnet

Gate a route

import express from 'express';
import { agentGate } from 'concordium-agentgate';
// import { paymentMiddleware } from '@x402/express'; // official x402 seller middleware

const app = express();
app.get('/paid/quote',
  agentGate({ network: 'testnet' }),   // 401 no badge · 403 unregistered/revoked/tampered · 503 registry down
  paymentMiddleware(/* your x402 config */),
  (req, res) => res.json({ quote: '…', agent: req.agentGate.tokenAddress }));

Agents identify themselves with the X-Agent-Badge header. Its value is their badge, i.e. the CIS-2 token address such as Mf22soLh1NuZYFgBK8iSs. CAIP-19 form and a Concordium owner account are also accepted.

agentGate(options):

On success, the verified record is available as req.agentGate, and an X-AgentGate: verified; … header is set.

MCP server

Remote (hosted, free tier): https://agentgate.agentgate.workers.dev/mcp (Streamable HTTP). Local (stdio, queries Concordium directly, full record):

{ "mcpServers": { "agentgate": { "command": "npx", "args": ["-y", "-p", "concordium-agentgate", "agentgate-mcp"] } } }

Or run it locally with node mcp/server.js (stdio). The server exposes one tool:

• check_agent({ id, network }) returns VERIFIED / NOT VERIFIED plus the structured record.

Set AGENTGATE_MOCK=1 to use offline fixtures.

Static checker

Live at https://agentgate-source.pages.dev/agentgate/demo/ (or open docs/index.html locally). You can deep-link a check, e.g. ?id=Mf22soLh1NuZYFgBK8iSs&network=mainnet. The page queries Concordium's public endpoints directly from the browser (CORS is open), using the same registry.js as the library.

What is real and what is mocked

Tests use recorded real responses from the badge-check API (test/fixtures/). npm run test:live also hits the real endpoints.

Roadmap (toward the Dec 9, 2026 hackathon submission)

• [ ] Signed badge challenge: the agent proves control of its CIS-8 bound key or agent wallet, so a header can't be replayed.
• [ ] Cross-chain payer binding: resolve EVM/Solana x402 payers through CIS-8 (owner_of_key, agent_by_external_reference).
• [ ] End-to-end testnet demo: register an AgentGate demo agent with a mock testnet identity, pay through a real x402 facilitator on Concordium testnet, record a video.
• [x] Free preview tier, remote MCP server, framework examples.
• [ ] npm package concordium-agentgate (package.json ready).

Development

npm test          # node:test, offline
npm run test:live # adds live calls to Concordium public endpoints
npm run sync-docs # copy src/registry.js -> docs/registry.js (a test enforces they match)

Built by an AI builder agent (agentgate-builder) with human oversight.

Support

If AgentGate is useful to you, tips are welcome at 0x3c1A1E01e790Cd326495631B3b38Bd7068F08d6F (EVM: Ethereum, Base, and other EVM chains).

Agent trust kit

Four small x402 tools for agents that act on outside input. Same pay-per-call USDC on Base, free tiers, remote MCP:

Typical flow: verify the counterpart agent with AgentGate, check its domain or contact email with DomainCheck, read a page with WebRead, and check it with InjectScan before following anything in it.

License

MIT

agentgate-source: code mirror on Cloudflare Pages. All repos