x402 & the Agent Economy (Concept)

Payment rails for the paid tier, not for launch week. The public MCP opens free at launch week with the full Glamsterdam hardfork. A few weeks later — after usage data and hardening — x402 (USDC on Base) is how agents buy runs of new EIPs that are still ahead of that hardfork. First expected paid capability: frame transactions (EIP-8141). The cycle is on Pricing. Facilitator wiring is still build-in-public.

Why this matters

Humans and agents are equal customers. Agents don't sign up, manage API keys, or type in card numbers — they carry wallets, decide from a quote, and pay. They also find services (registries, other agents) without a person who has read our website. The commercial model is that whole loop: discover, quote, pay, retry.

Important framing: x402 is how agents access the deterministic oracle — not the product itself. The hook is ground truth for upcoming fork rules; payment is the permissionless on-ramp.

x402 — payment (after the open launch)

x402 revives the dormant HTTP 402 "Payment Required" status code as a standard for machine-to-machine payments.

The flow we're building for the paid tier:

1. Agent requests a simulation on the hosted MCP.
2. Server replies 402 Payment Required with a price (e.g. USDC on Base), quoted dynamically based on the request.
3. Agent signs a gasless stablecoin transfer authorization and retries with the signature in the header.
4. A facilitator verifies and settles the payment on-chain; the server then runs the simulation and returns the result.

The 402 quote is the product surface. Before the engine runs, an agent must be able to decide: price, chain, asset, what the payment buys, and what a failed payment means. Token-holder discounts, when they land, are a wallet check on that same path — never a human claim form. See Pricing.

Why it fits: permissionless, account-less, and built for agents paying for API access. We lean on existing middleware and facilitators (e.g. Coinbase/Stripe) rather than building settlement ourselves — wiring is the current engineering focus.

MCP — delivery (shipped as tools; hosted HTTP pending)

Agents need explicit, self-describing tools — not guessed REST endpoints. We deliver through an MCP server (see Agent API & MCP (Concept)): describe_capabilities, run_bytecode, run_transaction, run_block, generate_artifact, and inspect_artifact are implemented; the public HTTP transport ships at launch.

Discovery

Agents find tools through MCP registries (e.g. the official registry.modelcontextprotocol.io, plus gateways/marketplaces) and, later, through other agents. describe_capabilities is the catalogue after connect; registry metadata and an agent-complete 402 quote are the catalogue before. Humans allowlist high-stakes tools as one path. Registry listings are on the roadmap board. Human-facing distribution is the other lane.

Timing — why now

We're in a "Goldilocks window" in 2026: the standards have hardened (MCP for how agents talk, x402 for how agents pay), facilitators are in production, and domain-specific deterministic endpoints — like an EVM oracle for upcoming forks — are still sparse. The engineering core landed in summer 2026. Launch week puts hosted access in public, open and unpaid. x402 follows once that service has been used and hardened, on the EIPs that are still ahead of Glamsterdam.

A note on identity & anti-abuse

ERC-8004 (trustless agent identities) and simple on-chain checks (e.g. a minimum wallet balance) could give cheap, effective spam resistance without human-style signups — relevant to how we'd keep the service open yet protected (see Pricing & Cost Model). Directional only; not implemented.

Changelog

x402 Concept Changelog

1. v0.52026-10-01x402 moves to the post-launch paid tier (EIP-8141 first). Launch week is the open Glamsterdam MCP.
2. v0.42026-09-24402 quote as product surface; discovery via registries and other agents.
3. v0.32026-09-02x402 decided for launch week (USDC on Base) — rails not hook; facilitator wiring build-in-public.
4. v0.22026-09-02Oracle built — x402 framed as launch-week payment rails, not the product hook; MCP tools exist.
5. v0.12026-06-30Initial outline — x402 payment flow, MCP as delivery layer, registry discovery.

Add a one-line entry here whenever this concept changes.