@quackai/q402-mcp

MCP server for Q402 — gasless USDC, USDT, and RLUSD payments across 8 EVM chains, callable from Claude (Desktop / Code), OpenAI Codex CLI, and any other Model Context Protocol client.

🎟️ Free trial available (2026-05-19 → 2026-06-30) — 2,000 gasless transactions on BNB Chain (USDC + USDT), 30-day window, no card. One wallet signature: https://q402.quackai.ai.

Trial-scope policy: API keys minted under the free-trial program (plan: "trial") are restricted to BNB Chain with USDC/USDT — server-side enforcement, returns 403 TRIAL_BNB_ONLY otherwise. Paid API keys see the full 8-chain matrix at all times.

Claude can now reason about stablecoin payments end to end — quote a transfer across 8 chains, pick the cheapest route, and (optionally) settle the transaction over Q402's EIP-7702 relayer infrastructure. The recipient receives the full amount; the sender pays $0 in gas.

Quick start

The server speaks stdio MCP, so any MCP-compatible client can use it. The two paths verified end-to-end today are Claude (Desktop / Code) and OpenAI Codex CLI.

Claude Desktop / Claude Code

claude mcp add q402 -- npx -y @quackai/q402-mcp

Or edit claude_desktop_config.json directly:

{
  "mcpServers": {
    "q402": {
      "command": "npx",
      "args": ["-y", "@quackai/q402-mcp"]
    }
  }
}

Restart Claude Desktop and ask:

"Compare gas costs to send 50 USDC to vitalik.eth across all 8 Q402 chains."

OpenAI Codex CLI

Three install paths — pick the one that matches your workflow.

(a) Codex plugin marketplace (recommended — bundles the MCP config so users don't write TOML):

codex plugin marketplace add bitgett/q402-mcp
codex /plugins        # browse and install "q402"

This repo carries a Codex plugin manifest at .codex-plugin/plugin.json and a marketplace catalog at .agents/plugins/marketplace.json, so any signed-in Codex user can register it as a marketplace source and install with one click.

(b) Single MCP server via codex mcp add (no plugin wrapper — just register the stdio server):

codex mcp add q402 -- npx -y @quackai/q402-mcp

(c) Direct ~/.codex/config.toml edit (.codex/config.toml for per-project scope):

[mcp_servers.q402]
command = "npx"
args = ["-y", "@quackai/q402-mcp"]
startup_timeout_sec = 20.0

To enable real on-chain payments, pass the three live-mode env vars explicitly under env — Codex does not forward host env vars by default:

[mcp_servers.q402]
command = "npx"
args = ["-y", "@quackai/q402-mcp"]
startup_timeout_sec = 20.0
env = {
  # Two-key model: set whichever applies — both is best.
  # Auto-routing rule (same for q402_pay AND q402_batch_pay):
  #   chain="bnb" + Q402_TRIAL_API_KEY set  → Trial (free sponsored)
  #   anything else                          → Multichain (paid 8-chain)
  # Batch ambiguity: when auto would land on Trial AND recipients.length > 5,
  # q402_batch_pay returns status="ambiguous" WITHOUT executing so the agent
  # can ask the user — pass keyScope="trial" (first 5), "multichain" (all
  # paid), or call twice (5 free + remainder paid).
  # Both keys use the same q402_live_ prefix — the env var name is what
  # carries the scope, not the key string. Get the values from the
  # dashboard (each key has its own copy button per view).
  Q402_TRIAL_API_KEY        = "q402_live_...",         # BNB-only sponsored (from /event)
  Q402_MULTICHAIN_API_KEY   = "q402_live_...",         # paid 8-chain (from /payment)
  # Legacy fallback — used if neither scoped key above is set.
  Q402_API_KEY              = "q402_live_...",
  Q402_PRIVATE_KEY          = "0x

... [View full README on GitHub](https://github.com/bitgett/q402-mcp#readme)