x402_get_payment_info should not require Fireblocks credentials

[TateLyman]

Summary

x402_get_payment_info is described as a no-payment inspection tool, but it currently calls this.httpService.get(url) without overriding the default balance-check behavior. When a target returns a supported 402, HttpX402Service.get() defaults checkBalance to true, initializes FireblocksService, and requires FIREBLOCKS_API_KEY plus FIREBLOCKS_PRIVATE_KEY_PATH before it can return the payment preview.

That makes a read-only preview path depend on Fireblocks credentials even though no payment is being made.

Source path

In src/mcp-server.ts:

private async handleX402GetPaymentInfo(args: { url: string }) {
  const { url } = args;

  const response = await this.httpService.get(url);

In src/HttpX402Service.ts, get() defaults to balance checking:

const checkBalance = opts.checkBalance ?? true;
if (checkBalance) {
  this.fireblocksService = new FireblocksService();
  await this.fireblocksService.initialize(initChainId);
}

Impact

A user who only wants to inspect a merchant's 402 requirements from MCP can hit FIREBLOCKS_API_KEY not set in .env / private-key setup errors instead of seeing the amount/network/asset/payTo preview. This is especially surprising because the MCP tool description says it checks payment requirements without completing payment.

Suggested fix

Have x402_get_payment_info call the service in preview mode, for example:

const response = await this.httpService.get(url, {
  checkBalance: false,
  selection: "manual",
});

Optionally include a note in the returned preview that balance was not checked. x402_get_and_pay can keep check_balance=true as the default because that path may actually sign.

Verification

I ran a local build from a fresh clone of main:

npm ci
npm run build

Result: build passed. I did not use Fireblocks credentials, payment headers, wallets, private endpoints, or paid x402 calls.