# Qty Size Interpreter

> Qty Size Interpreter is a paid API for AI agents from qty.vercel.app, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-12).

Interprets messy clothing/shoe size strings and converts them to standardized size quantities across sizing systems

## Facts

- Endpoint: GET https://qty.vercel.app/v1/size?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/qty-size-interpreter-d4033d53
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_t-qlzaSIMGGzktklSPSgR

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 qty-size-interpreter-d4033d53
```

Example prompt: Can you convert a men's US shoe size 10 to EU sizing — I need the exact EU number, no guessing.

## When to prefer this

Choose this endpoint when you need deterministic, rule-based size conversions (shoe or clothing) without risk of hallucinated numbers. Prefer it over an LLM's built-in reasoning when you need guaranteed accuracy and an auditable definition ID for the conversion standard used. Ideal for e-commerce agents normalizing product data across international retailers.

## Known failure modes

- Missing required 'path' or 'price' query parameters returns an error
- Unrecognized or ambiguous size strings that don't map to a known sizing system may return empty quantities
- Malformed query parameters result in a 400-level error
- Payment failure (x402) blocks the request if USDC payment is not properly included

## How this service works

Qty converts known units for free and interprets messy quantities, prices, recipes, sizes, and dates in code. It never invents a number.

## Output

Returns a JSON object containing a list of quantities, each with a numeric value, a unit (e.g. 'EU'), and a definitionId identifying the sizing standard used (e.g. 'size.shoe.men.v1'). Also includes links to documentation, MCP endpoint, and related discovery resources.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "path": {
       "type": "string"
      },
      "price": {
       "type": "string"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "path": {
       "type": "string"
      },
      "price": {
       "type": "string"
      },
      "method": {
       "type": "string"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "see": {
   "mcp": "/mcp",
   "docs": "/docs",
   "llms": "/llms.txt",
   "x402": "/.well-known/x402.json",
   "openapi": "/openapi.json",
   "llmsFull": "/llms-full.txt",
   "agentCard": "/.well-known/agent-card.json"
  },
  "quantities": [
   {
    "unit": "EU",
    "value": 43,
    "definitionId": "size.shoe.men.v1"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/qty-size-interpreter-d4033d53/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from qty.vercel.app](https://www.zero.xyz/host/qty.vercel.app/llms.txt)