# agent402.tools Keyword Frequency Extractor

> agent402.tools Keyword Frequency Extractor is a paid API for AI agents from agent402.tools, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).

Extracts top keywords and two-word phrases by frequency from text, with stopwords removed, for routing, tagging, and deduplication.

## Facts

- Endpoint: POST https://agent402.tools/api/keywords
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent402-tools-keyword-frequency-extractor-123391c5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_mGkTRQ2vILJxpONLnV0D2

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 agent402-tools-keyword-frequency-extractor-123391c5 -d '<json body>'
```

Example prompt: Extract the top 20 keywords and two-word phrases from this article text, removing stopwords: 'Blockchain technology has transformed financial systems worldwide, enabling decentralized transactions and smart contracts that remove intermediaries from banking and lending processes.'

## When to prefer this

Use this endpoint when you need fast, deterministic keyword extraction without ML inference overhead — ideal for routing, content tagging, deduplication signals, or any pipeline where reproducibility and low cost matter more than semantic understanding. Prefer over LLM-based summarization when you need raw frequency-based signals.

## Known failure modes

- Text exceeds 500KB limit — request rejected with size error
- Invalid or missing text field — returns validation error
- Limit parameter out of range — may return default behavior or error
- Payment failure via x402 protocol — 402 response requiring USDC payment
- Empty text input — returns empty keyword list

## How this service works

Top keywords and two-word phrases by frequency (stopwords removed). Cheap, deterministic signal for routing, tagging, and dedup.

## Output

A ranked list of top keywords and bigrams extracted from the input text, with stopwords filtered out, ordered by frequency — up to the specified limit (default 15).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "text": {
   "type": "string",
   "description": "Text to analyze (max 500KB)"
  },
  "limit": {
   "type": "number",
   "description": "Max keywords (default 15)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "phrases": [
   {
    "term": "x402 protocol",
    "count": 2
   },
   {
    "term": "payment terms",
    "count": 2
   }
  ],
  "keywords": [
   {
    "term": "request",
    "count": 4
   },
   {
    "term": "payment",
    "count": 4
   },
   {
    "term": "agent",
    "count": 3
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent402-tools-keyword-frequency-extractor-123391c5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.tools](https://www.zero.xyz/host/agent402.tools/llms.txt)