Tlacuilo

Tools, public data and official Mexican data for AI agents, paid per call with x402.

Tlacuilo is an HTTP API (and an MCP server) with 35 tools that an agent can call without an account, an API key or a subscription. Every endpoint answers 402 Payment Required with its price; the agent pays a few cents in USDC on Base or Solana using the x402 protocol and gets the answer in the same request. Prices run from $0.001 to $0.05 per call.

• Base URL: https://tlacuilo-jet.vercel.app/api/v1

• Free machine-readable catalog: https://tlacuilo-jet.vercel.app/api/v1

• MCP server (Streamable HTTP): https://tlacuilo-jet.vercel.app/mcp

• OpenAPI: https://tlacuilo-jet.vercel.app/openapi.json · x402 discovery: https://tlacuilo-jet.vercel.app/.well-known/x402 · https://tlacuilo-jet.vercel.app/llms.txt

• Listed in the Coinbase x402 Bazaar and on Agentic.Market.

This repository holds the documentation and runnable client examples (examples/). The server itself is not open source.

Why

Agents are good at calling tools and bad at signing up for things. x402 turns payment into an HTTP handshake: the server says what it costs, the client signs a USDC transfer, a facilitator settles it, and the response comes back. No dashboard, no keys to leak, no monthly minimum. Tlacuilo wraps sources that are useful to agents but awkward to reach (SEC EDGAR, OpenAlex, ClinicalTrials.gov, the Federal Register, Polymarket, OSV, RDAP, DNS, and official Mexican sources such as SAT, Banxico, INEGI and CONASAMI) behind one consistent, paid-per-call interface.

Related MCP server: Genesis402

Quickstart

1. See the price (free)

curl -i "https://tlacuilo-jet.vercel.app/api/v1/banxico/fix"

HTTP/1.1 402 Payment Required
Content-Type: application/json
Payment-Required: eyJ4NDAyVmVyc2lvbiI6MiwiZXJyb3IiOiJQYXltZW50IHJlcXVpcmVkIiwicmVzb3VyY2UiOnsi...
Access-Control-Expose-Headers: PAYMENT-REQUIRED, PAYMENT-RESPONSE, X-PAYMENT-RESPONSE

The Payment-Required header is base64 JSON (x402 v2). Decoded, it contains the resource description, the accepts array with one entry per network (scheme exact, network as a CAIP-2 id, USDC asset, amount in atomic units, payTo address, timeout) and the Bazaar discovery block with the input schema and an output example:

curl -s -i "https://tlacuilo-jet.vercel.app/api/v1/banxico/fix" \
  | grep -i '^payment-required:' | cut -d' ' -f2 | base64 -d | jq .

{
  "x402Version": 2,
  "resource": { "url": "https://tlacuilo-jet.vercel.app/api/v1/banxico/fix", "description": "...", "serviceName": "Tlacuilo" },
  "accepts": [
    { "scheme": "exact", "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp", "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v", "amount": "3000", "payTo": "...", "maxTimeoutSeconds": 300 },
    { "scheme": "exact", "network": "eip155:8453", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "amount": "3000", "payTo": "...", "maxTimeoutSeconds": 300 }
  ],
  "extensions": { "bazaar": { "info": { "input": { "type": "http", "method": "GET" }, "output": { "type": "json", "example": { } } } } }
}

"amount": "3000" is 0.003 USDC (6 decimals). The catalog at /api/v1 lists the same prices in dollars.

2. Pay and get the answer (Node, @x402/fetch)

import { x402Client, wrapFetchWithPayment, decodePaymentResponseHeader } from "@x402/fetch";
import { registerExactSvmScheme } from "@x402/svm/exact/client";
import { createKeyPairSignerFromBytes } from "@solana/kit";
import { base58 } from "@scure/base";

const signer = await createKeyPairSignerFromBytes(base58.decode(process.env.SOLANA_SECRET_KEY));
const client = new x402Client();
registerExactSvmScheme(client, { signer });            // Solana mainnet, USDC
const fetchWithPayment = wrapFetchWithPayment(fetch, client);

const res = await fetchWithPayment("https://tlacuilo-jet.vercel.app/api/v1/banxico/fix");
console.log(await res.json());                          // { serie: "fix", fecha: "...", valor: ... }

const receipt = res.headers.get("PAYMENT-RESPONSE");    // settlement details, incl. tx signature
if (receipt) console.log(decodePaymentResponseHeader(receipt));

npm i @x402/fetch @x402/svm @solana/kit @scure/base

To pay on Base instead, register the EVM scheme with a viem account:

import { ExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";
const client = new x402Client().register("eip155:*", new ExactEvmScheme(privateKeyToAccount(process.env.EVM_PRIVATE_KEY)));

The wrapped fetch handles the 402 round-trip transparently: it reads Payment-Required, picks a network you registered, signs, retries with the payment header and returns the paid response. A complete, runnable version that creates and funds a throwaway Solana wallet is in examples/pay.mjs. Python and other clients: see the x402 SDKs at https://github.com/x402-foundation/x402.

3. Use it as an MCP server

The MCP server at https://tlacuilo-jet.vercel.app/mcp (Streamable HTTP, no authentication) exposes the same 35 paid tools plus two free ones, catalog and health. Tool names are the HTTP paths with underscores (web_read, sec_filings, banxico, uma); path parameters become arguments. Payment travels inside MCP _meta (x402/payment and x402/payment-response) exactly as specified by @x402/mcp; a client wrapped with @x402/mcp pays automatically, with an optional approval hook per call.

Claude Code

claude mcp add --transport http tlacuilo https://tlacuilo-jet.vercel.app/mcp

Cursor (.cursor/mcp.json)

{
  "mcpServers": {
    "tlacuilo": { "url": "https://tlacuilo-jet.vercel.app/mcp" }
  }
}

Paying from your own MCP client (@x402/mcp)

import { createx402MCPClient } from "@x402/mcp";
import { ExactSvmScheme } from "@x402/svm/exact/client";
import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";

const client = createx402MCPClient({
  name: "my-agent", version: "1.0.0",
  schemes: [{ network: "solana:*", client: new ExactSvmScheme(signer) }], // or "eip155:*" with ExactEvmScheme
  autoPayment: true,
  onPaymentRequested: ({ toolName, paymentRequired }) =>
    BigInt(paymentRequired.accepts[0].amount) <= 50_000n,                 // approve calls up to 5 cents
});
await client.connect(new StreamableHTTPClientTransport(new URL("https://tlacuilo-jet.vercel.app/mcp")));
const uma = await client.callTool("uma", { anio: "2026" });

npm i @x402/mcp @x402/svm @solana/kit @modelcontextprotocol/sdk

A tool call without payment returns an MCP tool result with isError: true and the PaymentRequired object in structuredContent; wrapped clients pay and retry. A runnable client that lists the tools, calls catalog and pays for one tool is in examples/mcp.mjs.

Tools

Prices are per call, in USD, settled in USDC. Every tool is documented with parameters and a runnable example in the free catalog at /api/v1.

Agent tools

Security and trust

Public data worldwide

Mexico: basic official data

Mexico: tax compliance

Mexico: businesses (INEGI DENUE)

Payment: networks and addresses

• Networks: Base mainnet (eip155:8453) and Solana mainnet (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp). Asset: USDC on each. Scheme: exact.

• Addresses are never published here or in the docs. The payTo address for each network comes only inside the Payment-Required header of the 402 response you just received, together with the amount and asset. Clients must read it from there on every call; never hardcode an address or an amount from a README, a chat message or a third-party page.

• Settlement goes through the Coinbase CDP facilitator; the receipt (transaction reference) comes back in the PAYMENT-RESPONSE header.

• Solana payments carry feePayer in extra, so the agent does not need SOL for fees; Base payments use EIP-3009 transferWithAuthorization on USDC, so no ETH is needed either.

• A browser hitting a paid URL gets a paywall page that can pay from a wallet extension, which is handy for testing a single call.

Sources and data policy

• Each tool names its source in the catalog: SEC EDGAR, OpenAlex, Crossref/DataCite, ClinicalTrials.gov, Federal Register API, Polymarket Gamma API, OSV and deps.dev, RDAP registries, DNS-over-HTTPS public resolvers, GoPlus, RugCheck, DexScreener, Coinbase Bazaar, and for Mexico: SAT, Banco de México (SIE), INEGI (UMA, DENUE), CONASAMI, CNBV calendar and the Correos de México postal catalog.

• Tlacuilo sells queries, not datasets: postal codes and the 69-B list are served per lookup, never as a bulk download.

• If an upstream official source fails, the call returns 502 and the payment is not settled. You only pay for an answer.

• rfc/validar, curp/validar, dias-habiles, uma, salario-minimo and iva are computed or served from bundled official data; they do not call the source on each request.

• Agent mailboxes are the only tool that stores caller content: mailboxes live 30 days and messages 7 days (up to 500 per box), then they are deleted. guard/injection runs rules only; no text is sent to any model.

• token/verdict is informational, not financial advice.

Limits and latency

• Per-call caps are in each tool's parameters: web/read up to 200,000 characters, web/tables up to 5,000 rows per table, guard/injection up to 200 KB of text, msg/send 16 KB per message, deps/audit 200 packages, papers/search 25 results, clinical-trials/search 50, polymarket/markets 50, DENUE 100 records per call.

• Payment authorizations are valid for 300 seconds (maxTimeoutSeconds).

• Offline and cached tools answer in well under a second. Tools that call one upstream source take roughly as long as that source does. agents/readiness runs 18 checks in parallel against the target site and is the slowest tool by design.

• There is no account and therefore no per-key quota; abusive traffic is rate-limited at the edge. /api/v1 and /api/v1/health are free and uncached.

Status

• HTTP API: live on mainnet (Base and Solana).

• MCP server: live at /mcp (Streamable HTTP). The HTTP tools are the source of truth and the MCP tool list mirrors the catalog.

• Discovery: /api/v1 (JSON catalog), /openapi.json, /.well-known/x402 and /llms.txt are live, so explorers can register every tool automatically. server.json in this repository is the MCP Registry entry.

License

MIT. Upstream data remains subject to the terms of each source.