> For the complete documentation index, see [llms.txt](https://cluster-protocol.gitbook.io/whitepaper/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cluster-protocol.gitbook.io/whitepaper/agentic-infrastructure/agent-payment-rails-x402.md).

# Agent Payment Rails (x402)

x402 is not just a developer convenience: it is the economic layer that makes AI agents self-sufficient.

An agent with a USDC wallet on Base can:

1. Discover Cluster's inference API
2. Receive a 402 Payment Required response with pricing
3. Autonomously sign a payment and resubmit
4. Receive inference results
5. Use those results to take further on-chain actions

No human needs to create an account, generate an API key, or approve a transaction. The agent operates as an independent economic entity: earning, spending, and transacting on its own.

Combined with ERC-8004 identity, agents on Cluster are:

* **Identifiable**: verifiable on-chain identity
* **Economically autonomous**: pay for services via x402
* **Auditable**: all transactions settled on Base, fully traceable