BondLens

$0.25/call

Yield, duration, convexity & loan amortization.

POST /api/agent-services/bond/analyze

financebondfixed-incomeyield-to-maturitydurationconvexityloanamortizationx402agent

What it does

Deterministic fixed-income & loan analytics. Bond mode: solve price<->yield-to-maturity, current yield, Macaulay & modified duration, and convexity from the bond's terms. Loan mode (send principal + annualRate + termMonths): level-payment amortization with monthly payment, total interest/paid, and the full schedule. Pure math from caller-supplied terms — no market-data feed, no fabrication.

Price ↔ yield-to-maturity
Macaulay & modified duration, convexity
Level-payment loan amortization schedules

Example request

POST /api/agent-services/bond/analyze

{
  "faceValue": 1000,
  "couponRate": 0.05,
  "periods": 10,
  "frequency": 2,
  "yield": 0.06
}

Example response (HTTP 200)

Deterministic — the same inputs always return the same audited output.

{
  "service": "bondlens",
  "requestId": "bl-8e084b70",
  "type": "bond",
  "bond": {
    "price": 957.348986,
    "yieldToMaturity": 0.06,
    "currentYield": 0.052228,
    "couponPerPeriod": 25,
    "totalCoupons": 250,
    "macaulayDurationYears": 4.471679,
    "modifiedDurationYears": 4.341436,
    "convexityYears": 22.304728,
    "priceValuation": "discount"
  },
  "loan": null,
  "findings": [
    {
      "rule": "bond-valuation",
      "severity": "info",
      "why": "Whether the bond trades above (premium), below (discount), or at par.",
      "evidence": "price=957.348986 face=1000 -> discount",
      "fix": null
    }
  ]
}

Input schema

Top-level request fields. Nested shapes are shown in the example above and the OpenAPI spec.

Field	Type	Required	Description
type	string	—	Optional explicit mode: 'bond' or 'loan'. Auto-detected as loan when principal is present.
faceValue	number	—	Bond face/par value (default 1000).
couponRate	number	—	Bond annual coupon rate as a fraction, e.g. 0.05 for 5%.
periods	number	—	Bond periods to maturity (integer).
frequency	number	—	Bond coupon payments per year (default 2 = semiannual).
price	number	—	Bond clean price; supply to solve yield-to-maturity.
yield	number	—	Bond annual yield; supply to solve price. Provide exactly one of price or yield.
principal	number	—	Loan principal (presence selects loan mode).
annualRate	number	—	Loan annual interest rate as a fraction, e.g. 0.06.
termMonths	number	—	Loan term in months (integer).

How to call it over x402

1. Send the request. The first unpaid call returns HTTP 402 with an x402 payment challenge — $0.25, USDC on Base, and the recipient.
2. Pay per call. Your x402 client signs the USDC payment and retries automatically — no API key, no account, no subscription. New to x402?
3. Read the result. HTTP 200 returns the computed values plus evidence-backed findings.

With the x402 fetch client (Node / TypeScript)

import { wrapFetchWithPayment } from "@x402/fetch";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount(process.env.AGENT_WALLET_KEY);
const pay = wrapFetchWithPayment(fetch, account); // USDC on Base

const res = await pay("https://hermesplant.com/api/agent-services/bond/analyze", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
  "faceValue": 1000,
  "couponRate": 0.05,
  "periods": 10,
  "frequency": 2,
  "yield": 0.06
}),
});

const result = await res.json();

Inspect the 402 with curl

curl -i -X POST https://hermesplant.com/api/agent-services/bond/analyze \
  -H "content-type: application/json" \
  -d '{"faceValue":1000,"couponRate":0.05,"periods":10,"frequency":2,"yield":0.06}'
# → HTTP/1.1 402 Payment Required  (x402 challenge: price, USDC asset, Base network, recipient)
# → sign the USDC-on-Base payment and retry to receive HTTP 200

Prefer zero code? This endpoint is also exposed as a tool on the Hermes Plant MCP server, so an MCP-capable agent can call it with its own x402 wallet.