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x402-native · MCP-compatible · USDC settlement on Base

Market signals for the agent economy

SignalGrid delivers institutional-grade market intelligence as machine-readable signals. AI agents pay per request via x402 USDC micropayments. Governments and banks get sovereign-ready data with full provenance and audit trails.

agent-shell — x402 session
# USDC balance: $4.82
$ curl https://keystoneequityyieldsolutions.com/v1/tch/status
← 402 Payment Required · sign & retry
$ x402 pay 0.0001 USDC → settle(base) ✓
{
  "operator": "The Clearing House",
  "programme": "ACH — operational",
  "agentMicropay": { "stage": "unavailable" },
  "asOf": "2026-09-30",
  "dataType": "reference"
}▊
cost: 0.0001 USDC · settled on Base · provenance: every response names its source and stage

40

Paid endpoints, live

6

Discovery formats

$0.0001

Price per call

Base

Settlement chain

0

API keys required

Platform

Built for agents, trusted by institutions

Every feature serves both the autonomous agent pulling signals at 3am and the sovereign treasury auditing them at noon.

⚡

x402-Native Payments

Every endpoint is metered and settled in USDC over HTTP 402. No API keys, no invoices, no human in the loop — the agent signs and pays per call.

🔌

MCP-Compatible

Discovered as native tools by any MCP agent — Claude, GPT, or custom LLMs. tools/list is free; tools/call settles like any other call.

🛡️

Labelled Provenance

Every response states its dataType (live or reference), the source it came from, the asOf date, and the programme stage. An unverified rail is reported as unverified.

🌐

Multi-Chain Ready

Base settles today. The middleware supports Ethereum, Arbitrum, Optimism, Polygon and Avalanche; a chain only goes live here once it is funded and verified. Celo is not enabled — see /v1/dtcc/status style honesty applied throughout.

💰

Priced in Public

A single list price of $0.0001 per call, published per endpoint at /openapi.json — cost an entire workload before spending anything.

🏛️

Sovereign-Oriented

VASP licensing status, travel-rule checks, sanctions screening, CBDC corridor reporting and on-chain audit trails for institutional and public-sector due diligence.

What you can actually call

40 endpoints, every one reachable right now. Nothing behind a waitlist.

Each is tagged in this table as Live or Reference up front, and the paid payload repeats that tag with its source and as-of date, so an agent can tell fetched data from curated reference without trusting this page.

Live · on-chain

Tokenized yield

$0.0001
read from chain

Tokenized money-market fund and deposit yields, read live from the underlying contracts rather than a cached table.

/v1/tokenized-mmf/yield
Live · public data

Compliance & VASP

$0.0001
public sources

OFAC sanctions screening, travel-rule checks, audit trails, VASP licensing status and agent-identity eligibility.

/v1/compliance/sanctions-screen
Reference · sourced

Payment rails

$0.0001
curated, dated

Programme status for TCH, SWIFT gpi, Visa and Mastercard agent payments, DCIO/Zengin, Lightning and the EU digital euro — with the pilot claims labelled as pilots.

/v1/swift/status
Reference · sourced

Sovereign & CBDC

$0.0001
curated, dated

CBDC corridor status and eNaira programme reporting, each tagged with its verification stage and a link to the primary source.

/v1/gov/cbdc/enaira/status
Both ways in

REST or MCP

$0.0001
per call, either way

Every endpoint is a plain paid HTTP route and an MCP tool. Discovery is free: /.well-known/x402, /openapi.json, /llms.txt, /agents.txt.

POST /mcp · tools/list
How It Works

From request to settled signal in one round-trip

1

Agent requests an endpoint

Your agent calls a Keystone route. The server replies 402 Payment Required with the price, asset, chain and pay-to address.

2

Agent signs & retries

The agent signs a USDC micropayment authorization (EIP-3009) and retries with the payment attached. A facilitator verifies and settles on Base.

3

Data delivered, self-labelling

The response arrives with its dataType, source, asOf date and programme stage, so the agent can tell live data from curated reference without trusting the copy.

MCP Integration

One config block. Every endpoint as a native tool.

Any MCP-compatible agent discovers this service as native tools — no SDK, no wrapper code. initialize and tools/list are free; tools/call returns an x402 challenge, and paying it settles exactly like the plain HTTP route.

keystone_tokenized_mmf_yield

Tokenized money-market-fund and deposit landscape — $0.0001

keystone_compliance_sanctions_screen

Sanctions screening and the lists to screen against — $0.0001

keystone_swift_message_mt

SWIFT MT/MX catalogue — takes an mt argument — $0.0001

keystone_dtcc_ops_verb

DTCC operations namespace — control verbs refuse with 403 before any payment — $0.0001

// mcp_client_config.json { "mcpServers": { "keystone": { "url": "https://keystoneequityyieldsolutions.com/mcp", "transport": "streamable-http" } } }

Agent discovers 40 tools · x402 payment auto-managed · zero glue code

Settlement Network

Supported chains

Every signal call settles natively in stablecoins via x402. Base settles in production today. Additional chains are in active facilitator verification for banks and sovereign agents.

• Live now — the chain we settle on

Base

ACTIVE
USDC · eip155:8453

Ethereum

PENDING
USDC · eip155:1

Optimism

PENDING
USDC · eip155:10

Polygon

PENDING
USDC · eip155:137

Arbitrum

PENDING
USDC · eip155:42161

Avalanche

PENDING
USDC · eip155:43114

◈ Requested, not built — listed so you know what we will not quietly take your money for

Celo

NOT SUPPORTED
eip155:42220. The facilitator does not settle Celo, and the candidate USDC address we were given has no contract on-chain — so we cannot price or settle it. Reported as unavailable until that changes.

Solana / XRPL / Stellar

NOT IMPLEMENTED
No middleware support exists for these. EIP-3009 USDC settlement is an EVM model; porting it is engineering work we have not started, not a switch we can flip.

Arc / Tempo

NOT IMPLEMENTED
Same position. The five EVM chains above are the ones actually wired into the settlement middleware today.
Government & Bank Procurement

What we have not built yet

Banks and card networks ask for more than four payment fields before they will settle. We are not there yet. Here is the list of what does not exist, so nobody spends a procurement cycle discovering it later.

✕

Compliance Receipts

Not implemented. You can buy a screening call — /v1/compliance/sanctions-screen — but there is no ALLOW / REFER / DENY decision attached to each settlement.

✕

Travel Rule Data

Not implemented. Settlement is a plain EIP-3009 transferWithAuthorization. Originator and beneficiary fields are not transmitted.

✕

Delegation & Spend Controls

Not implemented. A permit carries no spending limit, transaction cap, duration or merchant-scope field.

✕

Jurisdictional Data Residency

Not implemented. One deployment, no regional pinning, no air-gapped relay. Data does not stay inside your jurisdiction.

✕

Reconciliation

Not a product. Every paid response returns the transaction hash in X-X402-Tx, which is the raw material for your own ledger.

✕

On-Prem or Private Cloud

Not implemented. No bare-metal, private-cloud or sovereign-tier relay exists today.

If a procurement cycle depends on any of the above, this platform is the wrong dependency right now. The live catalogue is the authoritative list of what is actually callable.

Pricing

Priced in public. One price point, no sales call.

Every paid endpoint is $0.0001 USDC — the same rate for standard programme status and for the heavier compliance and collateral-verification references. No seat count, no subscription, no negotiation — you can cost an entire workload before spending anything, straight from /openapi.json.

Agent

For autonomous agents & individual builders
$0.0001 / call
  • x402 pay-per-call — USDC on Base, EIP-3009
  • All 40 paid endpoints, each priced in the open catalogue
  • Free discovery: /.well-known/x402, /openapi.json, /llms.txt, /agents.txt
  • REST + MCP (POST /mcp, Streamable HTTP)
  • Rate limit: 30 req/min per IP
Start building
No key required

Integrator

For agents that need volume rather than tiers
$0.0001 / call, published
  • Identical price — no volume discount, no negotiation
  • Cheaper per call than any plan that adds a middleman
  • Every response self-labels its stage and source
  • Rate limit raised on request for funded clients
  • Additional chains enabled when funded and verified
Call an endpoint now

Institutional

For due diligence and research desks
Not offered
  • No bespoke SLAs, on-prem relay or air-gapped deploy exists today
  • Institutional needs are best served by reading the sourced reference data directly
  • Compliance routes (sanctions, travel rule, VASP licensing) are already public and priced per call
  • Extra settlement chains are added by funding and verifying them — not by selling them
Read the catalogue
FAQ

Questions, answered

What is x402 and how does it work?

x402 is an open payment protocol built on the HTTP 402 status code. When your agent requests a paid endpoint, the server responds 402 with payment instructions. Your agent signs a USDC micropayment (EIP-3009) and retries the request with payment attached. A facilitator verifies and settles on Base. No credit cards, no API keys, no human in the loop.

How much does each call cost?

A flat $0.0001 USDC per call. There are no tiers and the rate does not vary by endpoint. Every price is published per endpoint at /openapi.json. No subscription, no minimum, no negotiation.

Do I need a subscription or an API key?

No. Payment is the authentication: your signing key is the credential, so there is nothing to store, rotate or leak. Bring your own funded wallet and you are live on the first call.

Which chains do you support?

Base settles live today. The middleware is built for Ethereum, Arbitrum, Optimism, Polygon and Avalanche, but a chain is only advertised here once it is funded and verified end to end. Celo is not enabled — its facilitator support and exact EIP-3009 domain are still unresolved, and we would rather report that than take a payment we cannot settle.

Can I offer this to a bank or government?

Use it for due diligence. The compliance routes — sanctions screening, travel-rule checks, on-chain audit trails, VASP licensing status, CBDC corridor reporting — are public, per-call and priced identically to everything else. There is no bespoke on-prem relay, air-gapped deployment or jurisdictional data-residency product today, and we would rather say so than take a procurement cycle for something that does not exist.

Do you perform KYC or store PII?

No. Nothing here touches documents or personal data. The compliance endpoints read public sources and return public records. If you need document KYC, use a licensed provider directly.

How do I know which data is real?

Every response says so itself. dataType is live (fetched from a primary source) or reference (curated and dated). Each programme carries a stage — live, pilot, target or unavailable — plus a source and an asOf date, and unverified routes return an explicit reason instead of a confident-looking stub.

Your agent is one 402 away from its first paid call

A few thousandths of a cent per call. No card, no key, no subscription.

Get started