# INCOME 2 Agent Tools – HMAC-SHA256

> INCOME 2 Agent Tools – HMAC-SHA256 is a paid API for AI agents from earn-tools-backend.onrender.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Computes an HMAC-SHA256 hash of an input string using a provided key, returning the hex digest as a pay-per-call x402 microservice.

## Facts

- Endpoint: POST https://earn-tools-backend.onrender.com/hmac-sha256
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/income-2-agent-tools-hmac-sha256-9f2d4edb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5t2zPcSFVPCGwRUdigY6l

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability income-2-agent-tools-hmac-sha256-9f2d4edb -d '<json body>'
```

Example prompt: Compute the HMAC-SHA256 of the string 'order:12345:confirmed' using the secret key 'mysecretkey123' and give me the result.

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-call HMAC-SHA256 computation without spinning up your own crypto library or server — especially useful for AI agents operating in x402 micropayment ecosystems that need to sign payloads, verify webhook signatures, or produce keyed hashes at $0.001 per call with no subscription or setup required.

## Known failure modes

- Missing or empty key field returns an error
- Input string exceeding 500,000 characters is rejected
- Payment not provided or invalid x402 payment signature returns 402 Payment Required
- Malformed JSON body returns 400 Bad Request
- Service temporarily unavailable on cold-start (Render free tier spin-up latency)

## How this service works

Low-cost x402 pay-per-call tools for autonomous buyers. Web extraction returns static public pages as clean markdown; every payable operation declares x-payment-info and a 402 response. Free betas: Agent Purchase Guard adds retry-safe purchase intent controls; Outcome Router accepts a desired result plus max budget and autonomously discovers fulfillment, tries zero-dollar proof-of-work first, and supports buyer-signed x402 paid execution where available.

Buyer-signed paid HYDRA execution
- Outcome request: POST https://earn-tools-backend.onrender.com/outcome-router
- Paid execution: POST https://earn-tools-backend.onrender.com/outcome-router/execute/{requestId}
- First execution call returns the relayed Agent402 Smart Order Router x402 PAYMENT-REQUIRED challenge.
- An x402-capable buyer wallet signs locally and retries with PAYMENT-SIGNATURE.
- HYDRA forwards the proof and returns the routed result.
- HYDRA never receives the buyer private key or uses owner working capital.
- Current beta platform fee: $0. Higher paid tiers are not auto-escalated.

## Output

Returns a JSON object with ok: true and a result object containing the HMAC-SHA256 hex digest string and an operation field confirming 'sha256'.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "key": {
   "type": "string",
   "maxLength": 10000
  },
  "input": {
   "type": "string",
   "maxLength": 500000
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "result": {
   "result": "...",
   "operation": "sha256"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/income-2-agent-tools-hmac-sha256-9f2d4edb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from earn-tools-backend.onrender.com](https://www.zero.xyz/host/earn-tools-backend.onrender.com/llms.txt)