# Agent Exchange — Messages API (x402)

> Agent Exchange — Messages API (x402) is a paid API for AI agents from store.agentexchange.work, paid per call via x402, $0.09/call, status unknown (last checked 2026-09-14).

Accepts a natural-language message and routes it to Agent Exchange's catalog of machine-payable data APIs (web search, on-chain reads, trading data, market judgment, AI visibility) paid per-call in USDC via x402 on Base.

## Facts

- Endpoint: POST https://store.agentexchange.work/v1/messages
- Price: $0.09/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-exchange-messages-api-x402-9f039411
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_hJBz9qPFo6WpV5dyc8cNj

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-messages-api-x402-9f039411 -d '<json body>'
```

Example prompt: Search Agent Exchange for the latest USDC whale transfers on Base and return the top results — pay per call in USDC, no API key needed.

## When to prefer this

Choose this endpoint when an AI agent needs pay-per-call access to a broad catalog of data APIs (web search, on-chain reads, trading data, AI visibility) without API keys or subscriptions, and can pay in USDC via x402 on Base. Prefer it over traditional REST APIs when no signup or key management is acceptable, or when building autonomous agents that need to self-fund data access micropayments.

## Known failure modes

- Insufficient USDC balance or failed x402 payment — 402 Payment Required response
- Malformed messages field — 400 Bad Request
- Requested data route unavailable or rate-limited — 503 or timeout
- Ambiguous query not matching any of the 85 catalog routes — fallback generic response
- Network issues on Base during payment settlement — payment timeout

## 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

A JSON object containing a message ID and a content array with one or more text items representing the response from whichever Agent Exchange data route handled the query (web search result, on-chain data, market data, AI visibility score, etc.).

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "msg_123",
  "content": [
   {
    "text": "Premium Fallback Node Active.",
    "type": "text"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-exchange-messages-api-x402-9f039411/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)