sigtap Agent Tools

12 paid micro-tools for AI agents over x402 (HTTP 402, USDC on Base mainnet) plus a runnable MCP server. Pay per call ($0.0005-$0.01), no signup, no API keys - the signed payment IS the credential.

• HTTP API: https://sigtap-outreach-api.sigtap.workers.dev (15 resources registered on x402scan)
• MCP (Streamable HTTP): https://sigtap-mcp.sigtap.workers.dev/mcp (13 tools; discovery: /openapi.json, /llms.txt, server-card)
• Facilitator: PayAI (eip155:8453, asset USDC 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913)
• Python package: pip install sigtap-agent-tools — PyPI shim with the free-preview client + challenge decoder (python -m sigtap_agent_tools.probe runs all probes)
• Kit tier (humans): https://unnamedaiagent.github.io/sigtap-kit/ - AI Outreach Kit, $19, crypto checkout - free sampler PDF (no email needed)

Free touch (no wallet needed)

Route	What it returns
GET /	Free catalog: every tool with price, params, live URL
GET /score-preview?subject=...	Subject-line-only preview of the email grader
GET /hash-preview?text=...	sha256 + crc32 of the first 1000 chars
GET /preview/<paid-path>	Free truncated sample of ANY paid tool (e.g. /preview/tools/hash?text=hi, /preview/uuid) - locked demo input, paid_unlocks field tells you what paying adds
GET /openapi.json	Full OpenAPI with x-payment-info prices
GET /llms.txt	Agent-readable endpoint digest

Paid endpoints (price live-verified from /openapi.json)

Outreach intelligence (the money tools):

Endpoint	Price	Output
GET /deliverability?domain=	$0.003	SPF/DKIM/DMARC audit for a sending domain
GET /grade?to=&subject=&body=	$0.005	12-point cold-email score with concrete fixes
GET /template?...	$0.010	Personalized cold email from proven templates

Micro-tools ($0.001-$0.003):

Endpoint	Price	Output
GET /tools/crypto-price?from=BTC&to=USD	$0.002	Coinbase spot/buy/sell + spread %
GET /tools/domain-age?domain=	$0.003	Registration date, age, registrar (RDAP)
GET /tools/hash?text=	$0.0005	SHA-256/384/512, hex, base64(url), CRC32
GET /tools/json?data=	$0.001	Flatten to dot paths / rows to CSV
GET /tools/jwt-decode?token=	$0.001	JWT header+payload with safety flags
GET /tools/regex?pattern=&text=	$0.001	Matches, groups, count, ReDoS-risk heuristic
GET /tools/slug?text=	$0.001	Unicode-safe slug (incl. Cyrillic translit)
GET /tools/uuid?version=&count=	$0.0005	UUIDv4/v7, ULID, nanoid - batched
GET /tools/weather?lat=&lon=	$0.001	Current + next-3h temps (open-meteo)

x402 payment flow (one round-trip)

1. GET /tools/hash?text=hello without payment -> HTTP 402 with a PAYMENT-REQUIRED header (base64 JSON: resource, amount in USDC units, network eip155:8453, payTo, 300s timeout).
2. Any x402-aware client signs the exact USDC transfer and retries with a PAYMENT-SIGNATURE header (x402 v2; legacy v1 clients use X-PAYMENT).
3. 200 + result. First settled call also activates the listing on the PayAI facilitator's Bazaar discovery catalog.

Heads-up: the API is behind Cloudflare. Python's default Python-urllib User-Agent is blocked (403 error 1010). Any real UA works (requests, httpx, curl, axios pass as-is). Details in SKILL.md.

Call it from an agent: working x402 snippets

Tested minimal clients for the flow above — the official @x402/fetch SDK and a zero-dependency Python wire-format reference, both verified end-to-end with funded calls (2026-09-06 and 2026-09-07, on-chain settlement receipts on Base mainnet): gist: working x402 snippets against sigtap

import { wrapFetchWithPaymentFromConfig } from "@x402/fetch";
import { ExactEvmScheme } from "@x402/evm";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount(process.env.EVM_PRIVATE_KEY);
const fetchWithPayment = wrapFetchWithPaymentFromConfig(fetch, {
  schemes: [{ network: "eip155:8453", client: new ExactEvmScheme(account) }], // Base mainnet
});
const res = await fetchWithPayment(
  "https://sigtap-outreach-api.sigtap.workers.dev/tools/uuid?count=1&version=ulid");
console.log(res.status, await res.text());
// 200 {"version":"ulid","count":1,"ids":["0PD1VZG5KCE10V6W4YW2PSWP2T"]}

Status of client-side friction (full history in the gist): both reference clients are verified end-to-end with real paid calls — official @x402/fetch (2026-09-06) and the zero-dependency Python wire-format client (2026-09-07: 200 on /tools/slug, settled on-chain, tx 0xfc1b31c6…06f0, $0.001 USDC on Base). The intermittent missing/truncated PAYMENT-REQUIRED header observed on 2026-09-06 was fixed the same day (~21:00 UTC: 25/25 probes returned a full, base64-parsable x402 v2 header). If a 402 ever arrives without a parseable PAYMENT-REQUIRED header, retry and please open an issue. Occasional 502 {"error":"settlement temporarily unavailable","retry":true} while the facilitator settles — transient, succeeds on retry.

MCP server

• Hosted: https://sigtap-mcp.sigtap.workers.dev/mcp - Streamable HTTP, 13 tools, x402 v2 payments settled in-band: on a paid tool call the payment travels in params._meta["x402/payment"] (the official @x402/mcp contract) and the on-chain receipt comes back in result._meta["x402/payment-response"] - no HTTP headers involved. Wire-level walkthrough verified end-to-end on 2026-09-08 (settled tx 0x5de43ef45b95272b9bb9ad242a088f900ce61fd5de4a971279cf5856626fa3e3): MCP.md. Health: /health, card: /.well-known/mcp/server-card.json.
• This repo (mcp_server.py, Dockerfile): zero-dependency stdio server, Python 3 stdlib only. catalog, score_preview, hash_preview are free; paid tools proxy the live API and surface the real 402 block until settled. See SERVER.md. Registered in the Official MCP Registry as io.github.unnamedaiagent/sigtap-agent-tools.

Agent integration

• Skill for Claude Code / any SKILL.md-aware agent: see SKILL.md (indexed on skills.sh).

MCP one-liner (paid calls settle in-band; paste into any MCP client config):

{ "mcpServers": { "sigtap-agent-tools": { "type": "http", "url": "https://sigtap-mcp.sigtap.workers.dev/mcp" } } }

For raw-HTTP agents calling the MCP endpoint by hand: the payment goes in params._meta["x402/payment"] and the receipt in result._meta["x402/payment-response"] - the full wire format, with live request/response bodies and a zero-dependency Node client, is documented in MCP.md.

• Claude Desktop / MCP clients: hosted URL above, or docker stdio: docker run -i --rm sigtap-agent-tools.

Stats: GET /stats on the API (total paid calls, revenue, by route - public, no PII). Pricing may be adjusted upward; /openapi.json is always live.