Synthex X402 MCP Server

synthex-x402

Client SDK for Synthex Forge's paid x402 services. USDC on Base mainnet.

One call. The 402 → EIP-3009 signing → retry loop is handled for you, and verify() re-checks the Ed25519 signature on the answer locally, with no network call and no cost.

from synthex_x402 import call, verify

result = call("/v1/preflight", {"target": "example.com"})
print(result["body"]["verdict"])        # 'go' | 'caution' | 'avoid' | 'unknown'
print(verify(result["body"])["valid"])   # True — re-checked locally

import { call, verify } from 'synthex-x402'

const result = await call('/v1/preflight', { target: 'example.com' })
console.log(result.body.verdict)         // 'go' | 'caution' | 'avoid' | 'unknown'
console.log(verify(result.body).valid)   // true — re-checked locally

Install

pip install synthex-x402          # Python 3.9+
npm install synthex-x402          # Node 18+

Try it without spending anything

python3 -m synthex_x402 --mock     # Python
cd sdk/typescript && npm install && npm run mock

The mock runs the entire flow — 402, instruction parsing, signing, retry, signed result, local verification — against a local mock server with a throwaway key. Nothing leaves your machine and nothing is charged.

The remote MCP server

The same tools are available over the MCP streamable-HTTP transport:

POST https://x402.synthexforge.com/mcp

curl -X POST https://x402.synthexforge.com/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

• Manifest: https://x402.synthexforge.com/.well-known/mcp.json
• A2A agent card: https://x402.synthexforge.com/.well-known/agent.json
• Registry: com.synthexforge.x402/paid-agent-services on the official MCP Registry (registry.modelcontextprotocol.io)

The services

Every tool is a thin adapter over the same paid HTTP route, so the MCP surface and the HTTP surface can never disagree about price or behaviour.

Payment rail

Configuration

With no key configured, call() does not pay — it returns the payment_required instructions so you can decide.

Documentation

Six how-to guides, served live at https://x402.synthexforge.com/docs:

1. Verify a settlement receipt on Base
2. Check an endpoint before paying it
3. Validate a payload before trusting it
4. Read a reference rate with staleness
5. Buy and redeem a pass
6. Prove a verdict was ours

Layout

sdk/python/          the Python package (PyPI: synthex-x402)
sdk/typescript/      the TypeScript package (npm: synthex-x402)
glama.json           Glama registry metadata

Development

# Python
cd sdk/python && pip install -e . && python3 -m synthex_x402 --self-test

# TypeScript
cd sdk/typescript && npm install && npm run self-test

Both self-tests run offline and assert, among other things, that the EIP-3009 digest is byte-identical to the x402 library's own.

License

MIT