Blog/The first cross-protocol agent
The first cross-protocol agent: CrewAI on ERC-8004 and x402
A worked example of an agent active on two protocol surfaces at once — and what AgentCrush sees when we cross the data.
In April 2026 we ran the first ERC-8004 reader sync against AgentCrush's index. Two agents matched: agentlab and CrewAI. CrewAI was the more interesting one. They are registered on Base (token #17997), and the registration declares x402_supported: true.
That single match is our first concrete cross-protocol data point. It is small. It is also the shape of what comes next.
The four-standard stack
Castle Labs published a useful frame in April: agent commerce is not one protocol but four interlocking standards.
- ◆x402 answers payment — can this HTTP resource be paid per call?
- ◆ERC-8004 answers identity — is this agent registered on-chain, by whom, on which network?
- ◆ERC-8183 answers commerce — can agents run a structured job lifecycle with escrow and evaluation?
- ◆ERC-8211 answers execution — how does the agent's work get verifiably done?
None of these is the same use case. None of them wins alone. A travel agent might use x402 for a weather API call, ERC-8004 for its own identity, ERC-8183 for the booking escrow, and ERC-8211 for the actual flight reservation. Different surfaces, same agent.
Most agent projects pick one. CrewAI is one of the first we have indexed that picked two.
What we actually see
CrewAI's profile on AgentCrush surfaces both rails. From the ERC-8004 side: a Base registration at token #17997, owner address resolved, network confirmed. From the x402 side: their registration metadata declares x402 support — meaning a downstream agent reading the registry knows it can attempt machine payment.
This is the small, specific thing that matters. An agent reading the ERC-8004 registry can now act on more than identity. It can route the next decision: this agent is registered, on this chain, and accepts payment via this rail. That's a routing decision a protocol-neutral intelligence layer can make on behalf of the calling agent.
Today, exactly two agents in our index do this. We expect that number to grow quickly.
Why we don't pick
AgentCrush is the layer above the protocols, not on them. We track across — we do not back any single standard.
That is a deliberate position. The protocols compete with each other. The intelligence layer profits from all of them shipping. CrewAI's two-protocol presence is not a victory for ERC-8004 or for x402. It is a data point about an agent that decided one surface was not enough.
What we expect to see next
A few specific things, in rough order of likelihood:
More cross-protocol agents. ERC-8004 has 181,000+ registrations across networks per the 8004scan public registry. Agentic.Market reports more than 11,000 x402 sellers. The protocols themselves are scaling. The intersection is two. Six months from now we expect the intersection to be in the hundreds, then thousands.
ERC-8183 jobs as the next signal. ERC-8004 says an agent exists. ERC-8183 says an agent is doing structured work with escrow and evaluation. That is higher-signal evidence of real activity, and we are scoping a reader for it.
The TradFi-side trust layer arriving in parallel. Experian's Agent Trust and Visa's Trusted Agent Protocol launched April 30. Different stack, same conceptual problem — verify the human behind the agent. We expect to track both surfaces alongside ERC-8004 within the next quarter.
Multi-rail will become the default. The agents that survive the next twelve months will support more than one payment surface. They will look more like CrewAI than like the single-protocol projects of late 2025.
Yesterday, AWS announced Bedrock AgentCore Payments with x402 support, Coinbase and Stripe wallet infrastructure, and the Coinbase x402 Bazaar MCP server exposed through AgentCore Gateway. The pattern is no longer hypothetical. The intelligence layer above these protocols becomes the place where agents — and the humans behind them — figure out which surfaces matter for which decisions.
Reading the registry yourself
If you build on either standard:
- ◆The ERC-8004 reader prototype is open source. It is at scripts/erc8004-reader-prototype.mjs in the AgentCrush repo. Read-only, no auth, runs against 8004scan.io's public API.
- ◆AgentCrush's MCP server exposes
lookup_agentandcompare_agentsfor any indexed handle, including CrewAI. You can call it from Claude Code or Cursor. No auth, no payment. - ◆CrewAI's profile is at agentcrush.xyz/agent/crewai. The cross-protocol surfaces are visible there.
If you have never executed an x402 buyer call before, our cheapest endpoint is the verification-status route at $0.005. That is the lowest-friction way to ship your first x402 buyer integration — a 5-cent end-to-end test against a live, indexed seller on Base mainnet. Code samples are on /developers.
For builders thinking about which standards to support — that question is exactly what our Agent Commerce Readiness Audit answers. We have shipped three x402 endpoints on Base ourselves. We can tell you which surfaces you actually need and which you can skip.
The first cross-protocol agent is one. The interesting question is the second hundred.
References: Castle Labs, “The Beginning of Agentic Finance” (April 2026); 8004scan.io public registry; Agentic.Market live stats. AgentCrush ERC-8004 reader prototype: scripts/erc8004-reader-prototype.mjs.