# sigtap MCP
> MCP server (Streamable HTTP) for outreach agents. 12 paid micro-tools + free catalog.
> One signature per call. No keys. x402 (USDC on Base mainnet, eip155:8453), PayAI facilitator.

## Connect
- MCP endpoint: https://sigtap-mcp.sigtap.workers.dev/mcp (POST JSON-RPC; initialize, tools/list, tools/call)
- Free routes: GET /health, GET /openapi.json, GET /.well-known/mcp/server-card.json, GET /llms.txt

## Tools (price per call, USDC on Base)
- deliverability_audit - $0.003: SPF/DKIM/DMARC deliverability audit for a sending domain
- email_grade - $0.005: 12-point cold email score with concrete fixes
- email_template - $0.01: Personalized cold email from proven templates
- hash_text - $0.001: SHA-256/384/512, hex, base64, base64url and CRC32 of a UTF-8 string
- jwt_decode - $0.001: Decode a JWT header+payload with safety flags (never verifies the signature)
- uuid_batch - $0.001: Batch random IDs: UUIDv4, UUIDv7, ULID or nanoid
- slugify - $0.001: Unicode-aware url-safe slug (latin + Cyrillic transliteration)
- json_tools - $0.001: Flatten JSON to dot paths or convert rows to CSV
- regex_test - $0.001: Regex matches with groups, count and a backtracking-risk heuristic
- crypto_price - $0.002: Coinbase spot/buy/sell price with spread percent
- domain_age - $0.003: Domain registration date, age in days and registrar via RDAP
- weather - $0.001: Current weather + next 3h temperatures (open-meteo)
- catalog - FREE: list all tools with prices and the payment rail

## Payment
- Paid tools/call without payment returns JSON-RPC error -32000.
- error.data.paymentRequired is the base64 x402 payment-required payload (scheme exact, network eip155:8453, amount in USDC smallest units).
- Sign the payment (x402 v2, EIP-3009 authorization) and retry the same tools/call with the PAYMENT-SIGNATURE header.

API twin (same tools, raw HTTP): https://sigtap-outreach-api.sigtap.workers.dev