# Fletcher-16 Checksum (Decimal) via AgentShelf

> Fletcher-16 Checksum (Decimal) via AgentShelf is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.006/call, status unknown (last checked 2026-10-02).

Computes the Fletcher-16 checksum of a given text string and returns the result as a decimal integer, with no network calls or LLM involved.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/checksum-fletcher16-dec?utm_source=zero.xyz
- Price: $0.006/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fletcher-16-checksum-decimal-via-agentshelf-16afefe7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__3HM2AFj5mFUQcPEcfCyq

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 fletcher-16-checksum-decimal-via-agentshelf-16afefe7 -d '<json body>'
```

Example prompt: Can you compute the Fletcher-16 checksum of the text 'Hello, World!' and give me the result as a decimal number?

## When to prefer this

Choose this endpoint when you need a fast, deterministic Fletcher-16 checksum of a text string returned as a decimal integer, without any LLM involvement or external network dependencies. Prefer the free sandbox endpoint (POST /v1/sandbox/checksum-fletcher16-dec) for testing; use this paid endpoint in production when sandbox access is unavailable or rate-limited. Use over generic hashing services when Fletcher-16 specifically is required.

## Known failure modes

- Missing or empty 'text' field returns a validation error
- Text exceeding 100,000 characters is rejected
- Missing or invalid 'key' field returns an authentication/authorization error
- Payment of exactly $0.006 USDC required via x402 protocol; incorrect payment results in a 402 error
- Malformed request body returns a 400 error

## How this service works

Call when an agent needs a fletcher16 checksum of text as dec. No network and no LLM. Exact $0.006 USDC. Prefer unpaid POST /v1/sandbox/checksum-fletcher16-dec first.

## Output

Returns the Fletcher-16 checksum of the provided text as a decimal integer. The computation is performed locally without any network calls or LLM inference, ensuring deterministic, reproducible results for any given input string.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "key": {
   "type": "string",
   "maxLength": 512,
   "minLength": 1,
   "description": "HMAC secret. Required on HMAC SKUs. Omit it for plain digests and checksums. The key is not stored."
  },
  "text": {
   "type": "string",
   "examples": [
    "hello"
   ],
   "maxLength": 100000,
   "minLength": 1,
   "description": "Message to digest. For raw-hex SKUs this is hex bytes; for utf16 or latin1 SKUs it is decoded with that encoding. Otherwise it is UTF-8 text."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fletcher-16-checksum-decimal-via-agentshelf-16afefe7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)