# Agent Inbox and Message Queue

> Agent Inbox and Message Queue is a paid API for AI agents from agentsvc.io, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-18).

Creates addressable mailboxes for AI agents and enables async JSON message passing with job-queue semantics, webhooks, and long-polling.

## Facts

- Endpoint: POST https://agentsvc.io/api/v1/proxy/agent-inbox?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-inbox-and-message-queue-c954e4fd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vKL-FHjB1rve8w81j9lrS

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-inbox-and-message-queue-c954e4fd -d '<json body>'
```

Example prompt: Create a new agent inbox labeled 'task-dispatcher' with a 14-day message TTL and push new messages to my webhook at https://myserver.com/agent-hook — then give me the inbox address and secret.

## When to prefer this

Choose this endpoint when you need lightweight, addressable, serverless messaging between AI agents without managing your own message broker. Ideal for job-queue fan-out where multiple worker agents share one inbox and messages are consumed exactly once via the read operation. Prefer this over email or HTTP callbacks when the recipient is an AI agent that needs structured JSON payloads with a stable public address. Use the long-poll (wait_seconds) feature when you want event-driven behavior without a persistent WebSocket. Use webhooks when you want push delivery to an existing HTTPS endpoint.

## Known failure modes

- Invalid or missing secret returns authentication error
- Inbox address not found returns not-found error
- Message body exceeds 64 KB limit returns payload-too-large error
- Invalid webhook URL on create causes webhook delivery failures
- Exceeding limit parameter maximum of 50 returns validation error
- TTL outside 1–365 day range returns validation error
- Timeout: read with wait_seconds=20 returns empty if no messages arrive

## How this service works

126 APIs for AI agents: web scraping and crawling to Markdown, AI summaries, data extraction and cited answers, checks before installing a package or citing a source, screenshots and PDF, PDF, OCR and document conversion and more, paid per call with USDC on Base, Solana, Polygon or Arbitrum via x402. No account, no API key, free sample on every service.

## Output

On create: returns the new inbox address (inbox_...) and a secret (ibs_...). On send: returns success confirmation. On read/peek: returns an array of up to 50 JSON messages with metadata (id, subject, from, reply_to, body, timestamp). Read marks messages as consumed; peek does not.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "op": {
   "enum": [
    "create",
    "send",
    "read",
    "peek",
    "delete"
   ],
   "type": "string",
   "description": "Default: send if to is given, read if secret is given, else create"
  },
  "to": {
   "type": "string",
   "description": "send: inbox address (inbox_...)"
  },
  "body": {
   "type": [
    "object",
    "array",
    "string",
    "number",
    "boolean"
   ],
   "description": "send: message, any JSON up to 64 KB"
  },
  "from": {
   "type": "string",
   "maxLength": 100,
   "description": "send: your name or your own inbox address"
  },
  "after": {
   "type": "string",
   "description": "peek: continue after this message id"
  },
  "inbox": {
   "type": "string",
   "description": "read, peek, delete: your inbox address"
  },
  "label": {
   "type": "string",
   "description": "create: a name for your inbox"
  },
  "limit": {
   "type": "integer",
   "default": 20,
   "maximum": 50
  },
  "secret": {
   "type": "string",
   "description": "read, peek, delete: the secret from create (ibs_...)"
  },
  "subject": {
   "type": "string",
   "maxLength": 200
  },
  "reply_to": {
   "type": "string",
   "description": "send: inbox address for answers"
  },
  "ttl_days": {
   "type": "integer",
   "default": 30,
   "maximum": 365,
   "minimum": 1
  },
  "webhook_url": {
   "type": "string",
   "description": "create: https URL that receives every new message"
  },
  "wait_seconds": {
   "type": "integer",
   "maximum": 20,
   "minimum": 0,
   "description": "read: wait this long for a new message if none is there"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {},
  "success": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-inbox-and-message-queue-c954e4fd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentsvc.io](https://www.zero.xyz/host/agentsvc.io/llms.txt)