# x402 AI Tools – Key Phrase Extraction

> x402 AI Tools – Key Phrase Extraction is a paid API for AI agents from ai.kagurazaka.dev, paid per call via x402, $0.008/call, status unknown (last checked 2026-10-30).

Extracts key noun phrases from text using Amazon Comprehend, returning each phrase with its character offsets and confidence score, with automatic language detection.

## Facts

- Endpoint: POST https://ai.kagurazaka.dev/v1/key-phrases?utm_source=zero.xyz
- Price: $0.008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-ai-tools-key-phrase-extraction-caa31339
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_l3TXshnSLALfaKO6hfyvd

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 x402-ai-tools-key-phrase-extraction-caa31339 -d '<json body>'
```

Example prompt: Can you pull out the key phrases from this paragraph: 'The new electric vehicle features a 400-mile range, fast charging capability, and an advanced autopilot system that rivals competitors in the premium segment.' — I don't need to specify the language, it's English.

## When to prefer this

Choose this endpoint when you need structured, offset-aware key phrase extraction with confidence scoring across 12 major languages, powered by Amazon Comprehend. It is especially useful when you need to know exactly where in the text each phrase appears (via offsets), or when the input language is unknown and automatic detection is needed. Prefer it over generic NLP libraries when you want a managed, pay-per-call cloud NLP service without managing infrastructure.

## Known failure modes

- Text exceeds 5000 bytes — request rejected with an error
- Unsupported language detected — Comprehend cannot process it
- Empty or missing text field — validation error
- Language code provided does not match one of the 12 supported codes — error returned
- Network or Amazon Comprehend service unavailability — 5xx error
- Payment failure via x402 protocol — request not processed

## How this service works

Extracts the key noun phrases of a text with Amazon Comprehend, with their offsets and scores. Supports en, es, fr, de, it, pt, ar, hi, ja, ko, zh, zh-TW; the language is detected when not given.

## Output

A list of key noun phrases found in the text, each with the phrase string, its start and end character offsets within the original text, and a confidence score (0–1) from Amazon Comprehend. The detected language code is also returned when language was not provided by the caller.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "text": {
   "type": "string",
   "description": "the text, up to 5000 bytes of UTF-8"
  },
  "language": {
   "type": "string",
   "description": "language code (en, es, fr, de, it, pt, ar, hi, ja, ko, zh, zh-TW); detected when omitted"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-ai-tools-key-phrase-extraction-caa31339/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from ai.kagurazaka.dev](https://www.zero.xyz/host/ai.kagurazaka.dev/llms.txt)