Skill: Savings goal

Bundled execution of the Savings goal workflow — How much do I need to save each month to hit $X in N years? Pin down the required contribution with a clever PV-discount trick: discount the target back to today, then call loan-payment with the discounted target as principal — the 'payment' the tool returns IS your required monthly savings. Same PMT formula a mortgage uses; different decision. One x402 payment runs 4 underlying tools (compound-interest, loan-payment, npv, irr); partial-success per step.

Input

Field	Type	Description
goal *	string	What you're saving for, with the target amount and time horizon (e.g. "save $1,000,000 for retirement in 30 years")
expectedReturn	string	Expected annual return as a decimal (default 0.07 = 7% for long-horizon equity; use 0.04 for bond-heavy or short-horizon goals)

Example output

{
  "pack": "savings-goal",
  "args": {
    "goal": "save $1,000,000 for retirement in 30 years",
    "expectedReturn": "0.07"
  },
  "steps": [
    {
      "slug": "compound-interest",
      "ok": true,
      "result": {}
    },
    {
      "slug": "loan-payment",
      "ok": true,
      "result": {}
    },
    {
      "slug": "npv",
      "ok": true,
      "result": {}
    },
    {
      "slug": "irr",
      "ok": true,
      "result": {}
    }
  ],
  "summary": "4/4 steps succeeded"
}

Try it — see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/skill/savings-goal \
  -H "Content-Type: application/json" \
  -d '{"goal":"save $1,000,000 for retirement in 30 years","expectedReturn":"0.07"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/skill/savings-goal", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "goal": "save $1,000,000 for retirement in 30 years",
    "expectedReturn": "0.07"
  }),
});

No wallet? Pay with compute

This is a pure-CPU tool, so an agent without a wallet can pay with proof-of-work instead of USDC: fetch a challenge, solve the sha256 puzzle (16 leading zero bits — a fraction of a second of CPU, no money, no AI tokens), and resend with the X-Pow-Solution header.

import { createHash } from "node:crypto";
const lz = (b) => { let t = 0; for (const x of b) { if (!x) { t += 8; continue; } t += Math.clz32(x) - 24; break; } return t; };
const c = await (await fetch("https://agent402.tools/api/pow/challenge?slug=skill-savings-goal")).json();
let n = 0;
while (lz(createHash("sha256").update(c.challenge + ":" + n).digest()) < c.difficulty) n++;
await fetch("https://agent402.tools/api/skill/savings-goal", { method: "POST", headers: { "X-Pow-Solution": c.token + ":" + n, "Content-Type": "application/json" }, body: JSON.stringify({"goal":"save $1,000,000 for retirement in 30 years","expectedReturn":"0.07"}) });

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