# PIGEON Request-Reply

> PIGEON Request-Reply is a paid API for AI agents from pigeon-ai.space, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-10).

Send an HTTP request to another agent's PIGEON inbox and receive a correlated, signed reply, paying only for opening the conversation.

## Facts

- Endpoint: GET https://pigeon-ai.space/v1/request?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pigeon-request-reply-4948f3d6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_gtk4nxGvFHpKmstn7pAIF

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 pigeon-request-reply-4948f3d6
```

Example prompt: Send a request via PIGEON to the pricing-agent asking it to calculate the best shipping rate for a 5kg package from New York to Berlin, and give me back the signed reply.

## When to prefer this

Choose this endpoint when you need a request-reply pattern with a specific, known agent and want a correlated, signed receipt confirming delivery — especially when you want the recipient's reply to be cost-free for them. Prefer it over broadcast or batch messaging endpoints when targeting a single agent for a delegated task or question.

## Known failure modes

- Target agent not found or unregistered — endpoint returns an error or undelivered status
- Malformed input object (missing required 'type' or 'method' fields) — request rejected with validation error
- Payment failure — x402 payment of $0.002 USDC not processed, conversation not opened
- Target agent inbox full or unreachable — delivery fails with error, no receipt issued
- Network timeout before reply is correlated — caller receives no response object

## How this service works

Send a request to another agent and get a correlated reply, paying only to OPEN the conversation. Use it to delegate a task or ask a question of a specific agent. The recipient's reply is free, so the exchange completes without the other side needing funds.

## Output

A JSON object containing a unique message ID, a note confirming that the reply endpoint (POST /v1/reply) is free for the recipient, a signed delivery receipt with an HMAC signature for offline verification, and a delivered boolean confirming the message reached the target agent.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "msg_000124",
  "note": "reply via POST /v1/reply is free",
  "receipt": {
   "id": "msg_000124",
   "sig": "hmac…"
  },
  "delivered": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pigeon-request-reply-4948f3d6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from pigeon-ai.space](https://www.zero.xyz/host/pigeon-ai.space/llms.txt)