Touchstone Assay — For agents

For agents

Touchstone Assay's four MCP tools, live on Base Sepolia — a testbed, not traction. get_index is free; the other three settle in USDC over x402 via Circle Gateway.

MCP config

Streamable HTTP. Paste this into a client that supports remote MCP servers.

{
  "mcpServers": {
    "touchstone-assay": {
      "url": "https://mcp.touchstoneassay.com/mcp"
    }
  }
}

Machine-readable: https://prints.touchstoneassay.com/mcp.json · https://prints.touchstoneassay.com/.well-known/llms.txt

Tools

Tool	Arguments	Price
`get_index`	`version?, date?`	free
`get_quote`	`task_class, model`	$0.001
`convert`	`model, input_tokens, output_tokens`	$0.001
`verify_receipt`	`chain, tx_hash`	$0.01

Prices settle in USDC on Base Sepolia (eip155:84532) via Circle Gateway nanopayments — an x402 402 challenge, paid, then the tool result. See docs/datum-quote.md for the full settlement shape.

What this is, plainly

A measurement standard and data publication — never "backed by," never a peg, never an oracle, nothing for sale. verify_receipt's on-chain read is live, reading the real deployed TouchstoneEscrow — see the Series page for the current print and the full methodology.

Verify a print yourself

Every print is signed and its fingerprint is recorded on chain. You can check one with no human in the loop. The whole procedure, with the contract addresses, is machine-readable at https://prints.touchstoneassay.com/verify.json.

GET the print JSON: https://raw.githubusercontent.com/petrkrulis2022/dated-siu-inference/main/data/prints/{print_id}.json (the index of every print is https://raw.githubusercontent.com/petrkrulis2022/dated-siu-inference/main/data/prints/index.json).
Remove exactly these fields and keep the rest as published: signature, public_key, anchor, superseded_by, correction_notes.
Canonicalise the rest with RFC 8785 (JCS), then take the keccak256 hash of its UTF-8 bytes (original Keccak padding, as Ethereum uses). That is the body hash.
For each chain the print was anchored on — the print's anchor (Base Sepolia), then each entry of anchor.additional_anchors (Arc Testnet) — GET {explorer}/api/v2/transactions/{tx_hash}/logs and find the PrintPosted event from that chain's contract whose bodyHash equals yours. Its timestamp is when the hash was first recorded. An entry recorded as failed or skipped has no transaction to check; the print is valid without it.

curl -O https://prints.touchstoneassay.com/verify-print.mjs
node verify-print.mjs 2026-10-14

The script does all four steps, for every chain the print carries, with plain Node 18 or later: no install, no keys. Exit code 0 only if the hash was computed, at least one anchor carrying it was found, and no anchor the print claims was missing or different. It does not check the signature.

Chain	TouchstoneAttestation	Publisher	Anchoring
Base Sepolia	`0xF60701793eD168ffd6e818e1DCcb600393297190`	`0x284ff2F8605Ff8AFeDa6959B856Bb7E6d48f845a`	live
Arc Testnet	`0x12b886b043feABc3d90bBae3ae206d22b208160d`	`0x284ff2F8605Ff8AFeDa6959B856Bb7E6d48f845a`	live from the print dated 2026-10-15

These contracts are on test networks. Anchoring proves that a print existed in this exact form by a given time; it does not prove the print's numbers are right.

Agent try it here

Checking this browser for WebMCP support…

Returns the current Dated SIU value, date, and status from the live, signed print.

Explains what one SIU is: the basket, the quality gate, how the print is computed.

Returns the current print's exchange-rate table — every constituent model's real cost, in SIU.

Free, read-only, no exceptions — never get_quote, convert, or verify_receipt, which stay paid, on the remote server only. These three call the same live MCP server as the config above. If your browser or agent supports WebMCP — an experimental W3C Community Group proposal, not yet a shipped standard — they're also registered directly with document.modelContext, in addition to the buttons.