Image description API: caption, OCR-style reading and visual Q&A

$0.01 per call · failed calls are never charged · no account or subscription: pay per call with a card key or USDC

Vision model for an image at a public URL: get a detailed description including any visible text, or pass a question to ask something specific about the image. Accepts PNG, JPEG, WebP and GIF up to 3 MB. Use for alt text, OCR-style reading of screenshots, chart reading and content checks.

When to use it

Write alt text for an image at a public URL
Read the text in screenshots and charts
Ask a specific question about the image

Guide: Describe image API

Buy credits by card (from $1) Example result (JSON)

Inputs

Name	Type	Description
`url` (required)	string	Absolute http(s) URL of a PNG, JPEG, WebP or GIF image (max 3 MB)
`question`	string	Optional question about the image (max 300 characters); default is a detailed description

Request

Over HTTP, with a card key from /credits:

curl -H "Authorization: Bearer adt_…" "https://tools.funwords.eu/describe?url=https%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2F4%2F47%2FPNG_transparency_demonstration_1.png"

Without a key, the same URL answers 402 Payment Required with x402 and MPP terms, so an agent with a wallet pays per call in USDC (Base, Polygon, Arbitrum or Solana over x402; Base or Tempo over MPP) and retries.

Example result

{
  "url": "https://upload.wikimedia.org/wikipedia/commons/4/47/PNG_transparency_demonstration_1.png",
  "question": "What colors are the dice?",
  "description": "The dice are blue, red, green, and yellow.",
  "model": "@cf/meta/llama-4-scout-17b-16e-instruct"
}

From an AI agent (MCP)

Add the MCP server to Claude, Cursor or any MCP client. This tool is describe, and the first 25 successful calls are free:

https://tools.funwords.eu/mcp

Questions

Which formats and sizes?

PNG, JPEG, WebP and GIF up to 3 MB, by public URL.

Which model answers?

A vision model on Workers AI; its exact name is returned in the model field.

How do I pay?

Each successful call costs $0.01; failed calls are not charged. This tool is not in the free calls; pay with card credits (from $1; the key goes in an Authorization header or, for clients that can only fetch a URL, as api_key= in the URL) or per call in USDC over x402 or MPP. No account is needed.