# Agent Exchange Chat Completions (LLM Inference)

> Agent Exchange Chat Completions (LLM Inference) is a paid API for AI agents from store.agentexchange.work, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).

Runs chat completions via a hosted LLM (Llama 3.1 8B) with pay-per-call USDC or monthly card billing

## Facts

- Endpoint: POST https://store.agentexchange.work/v1/chat/completions
- 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/agent-exchange-chat-completions-llm-inference-3e1279ca
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__-ZOheRGCH8yb0q-2YRTr

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 agent-exchange-chat-completions-llm-inference-3e1279ca -d '<json body>'
```

Example prompt: Send this conversation thread to a Llama 3.1 model and give me its reply — I want to pay per call without setting up a subscription: 'You are a helpful assistant. User: summarize the key risks of staking ETH.'

## When to prefer this

Choose this endpoint when you need a lightweight, OpenAI-compatible chat completions API with no signup friction, especially for agent workflows that benefit from x402 micropayment billing (pay $0.002 USDC per call) or a flat $29/month card option. It is ideal for prototyping, low-volume agent pipelines, or scenarios where avoiding a long-term LLM vendor contract matters. Prefer alternatives (OpenAI, Anthropic direct APIs) if you need GPT-4-class capability, function calling, vision, or higher-quality instruction following than Llama 3.1 8B provides.

## Known failure modes

- Payment not included or insufficient USDC — 402 Payment Required response
- Malformed messages field (not a valid conversation structure) — 400 Bad Request
- Model overloaded or Cloudflare Workers AI backend unavailable — 503 or timeout
- Missing or invalid API key for monthly-subscription callers — 401 Unauthorized
- Empty or null messages input — likely returns an error or empty completion

## How this service works

Machine-payable data APIs for AI agents across web search, on-chain reads, trading data, market judgment, and AI visibility. The canonical x402 catalog currently exposes 85 paid routes. Pay per call in USDC via x402 on Base. No API keys, no signup.

## Output

Returns an OpenAI-compatible JSON object containing: a unique completion ID, the model name used (@cf/meta/llama-3.1-8b-instruct-fp8), a choices array with the assistant's reply message, and a usage object with prompt_tokens, completion_tokens, and total_tokens counts.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "messages": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "chatcmpl-123",
  "object": "chat.completion",
  "choices": [
   {
    "message": {
     "role": "assistant",
     "content": "Hello."
    }
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-exchange-chat-completions-llm-inference-3e1279ca/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from store.agentexchange.work](https://www.zero.xyz/host/store.agentexchange.work/llms.txt)