# GET /api/v1/_siblings — List Sibling Services

> GET /api/v1/_siblings — List Sibling Services is a paid API for AI agents from scheduler.withzero.xyz, paid per call via MPP, price unknown, status unknown (last checked 2026-10-10, last successful call 2026-07-29).

Returns a list of sibling API services related to the scheduler.withzero.xyz platform, including their names, descriptions, and OpenAPI URLs.

## Facts

- Endpoint: GET https://scheduler.withzero.xyz/api/v1/_siblings?utm_source=zero.xyz
- Price: price unknown
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-10
- Last successful call: 2026-07-29
- Success rate: 100% of calls made through Zero
- Activations on Zero: 3
- Provider: scheduler.withzero.xyz
- Website: https://scheduler.withzero.xyz
- Canonical page: https://www.zero.xyz/c/scheduler-withzero-xyz-get-api-v1-siblings-list-sibling-services-927789f1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_MV5mQrXXP8xC4ym9btOVp

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 scheduler-withzero-xyz-get-api-v1-siblings-list-sibling-services-927789f1
```

Example prompt: What other services or APIs are available alongside this cron scheduler on withzero.xyz? I want to see the full list of sibling services and their OpenAPI docs.

## When to prefer this

Use this endpoint when an AI agent needs to auto-discover the full set of related APIs available from the scheduler.withzero.xyz platform — particularly useful for bootstrapping agent toolchains that need to enumerate and load OpenAPI specs dynamically. Prefer this over hardcoding sibling service URLs.

## Known failure modes

- Empty siblings array if no sibling services are registered
- 500 Internal Server Error if the service registry is unavailable
- Network timeout if the upstream service catalog is slow to respond

## How this service works

Known sibling capabilities. Names may appear in a task `tool_list`. 📖 Full guide: https://scheduler.withzero.xyz/llms.txt

## Output

Returns a JSON object with a 'siblings' array, where each item contains: 'name' (string), 'description' (string), and 'openapi_url' (string) pointing to that sibling service's OpenAPI specification. This is a service discovery/catalog endpoint.

## Example request

```json
{}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "siblings"
 ],
 "properties": {
  "siblings": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "name",
     "description",
     "openapi_url"
    ],
    "properties": {
     "name": {
      "type": "string"
     },
     "description": {
      "type": "string"
     },
     "openapi_url": {
      "type": "string"
     }
    },
    "additionalProperties": false
   }
  }
 },
 "additionalProperties": false
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/scheduler-withzero-xyz-get-api-v1-siblings-list-sibling-services-927789f1/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from scheduler.withzero.xyz](https://www.zero.xyz/host/scheduler.withzero.xyz/llms.txt)