# GEDX402 uform-gen2-qwen-500m Image Captioning

> GEDX402 uform-gen2-qwen-500m Image Captioning is a paid API for AI agents from media.gedx402.com, paid per call via x402, $0.415/call, status unknown (last checked 2026-09-15).

Generates a natural language caption or answer from a base64-encoded image using the UForm-Gen2-Qwen-500M vision-language model, payable via USDC on multiple chains with no API key required.

## Facts

- Endpoint: GET https://media.gedx402.com/v1/caption/uform-gen2-qwen-500m
- Price: $0.415/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/gedx402-uform-gen2-qwen-500m-image-captioning-d59d50fb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_GEywRtMMAyHeGIbhIbZ9N

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 gedx402-uform-gen2-qwen-500m-image-captioning-d59d50fb
```

Example prompt: Can you look at this image (I'll send it as base64) and describe what's in it — up to 200 tokens? No specific question, just a general caption.

## When to prefer this

Choose this endpoint when you need lightweight, fast image captioning or visual QA without managing API keys, billed per-call via USDC on Base, Polygon, Arbitrum, World, or Solana. Ideal for agents that need to caption or describe images on demand in a pay-as-you-go fashion using the x402 payment protocol.

## Known failure modes

- Invalid or malformed base64 image data returns an error
- Missing required 'image' field causes a bad request
- max_tokens too large may exceed model limits
- Payment not fulfilled results in HTTP 402 response
- Unsupported image format (non-JPEG/PNG) may fail silently or produce poor output

## How this service works

x402 workers ai. pay with usdc on base, polygon, arbitrum, world, or solana. no api keys.

## Output

A JSON object with a 'description' field containing a natural language caption or answer about the provided image, e.g. {"description": "A sunset over mountains."}

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "image": {
   "type": "string",
   "description": "Base64-encoded image for multimodal input."
  },
  "prompt": {
   "type": "string",
   "description": "Optional question or instruction about the image."
  },
  "max_tokens": {
   "type": "integer",
   "description": "Maximum tokens in the vision model response."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "description": "A sunset over mountains."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/gedx402-uform-gen2-qwen-500m-image-captioning-d59d50fb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from media.gedx402.com](https://www.zero.xyz/host/media.gedx402.com/llms.txt)