# Create a custom object link

> `POST` `/v1/custom-object-links`

URL: https://www.agencytitan.com/docs/tag/custom-object-links/POST/v1/custom-object-links

Operation ID: `custom_object_links_create`

Tag: [custom_object_links](https://www.agencytitan.com/docs/tag/custom-object-links.md)

## Description

Creates an idempotent source-authorized link to a custom-object record. Cardinality and labels are derived from the field/component definition.

## Parameters

- `Idempotency-Key` (header, required, `string`) — Caller-generated key for deterministic command replay (1-255 characters).

## Request body

- Required: yes
- Content-Type: `application/json`
  - Type: `object`
  - Properties:
    - `component_id` (`string`)
    - `field_definition_id` (`string`)
    - `is_primary` (`boolean`)
    - `sort_order` (`integer`)
    - `source_entity_id` (`string`, required)
    - `source_entity_type` (`string`, required)
    - `target_record_id` (`string`, required)

## Responses

- `200` (`application/json`): Successful response.
  - Type: `object`
  - Properties:
    - `data` (`object`, required)
- `400` (`application/json`): Request validation failed (unknown or out-of-range parameters/properties are rejected).
  - Type: `object`
  - Properties:
    - `error` (`object`, required)
- `401` (`application/json`): Missing, invalid, expired, or revoked bearer token.
  - Type: `object`
  - Properties:
    - `error` (`string`, required)
    - `error_description` (`string`, required)
- `403` (`application/json`): The authenticated user does not have permission for this operation.
  - Type: `object`
  - Properties:
    - `error` (`object`, required)
- `404` (`application/json`): The requested resource was not found.
  - Type: `object`
  - Properties:
    - `error` (`object`, required)
- `409` (`application/json`): The request conflicts with an existing record or partially applied.
  - Type: `object`
  - Properties:
    - `error` (`object`, required)
- `429` (`application/json`): Per-tenant rate limit exceeded (600 requests/minute across all /v1 REST endpoints). The Retry-After header indicates how many seconds to wait.
  - Type: `object`
  - Properties:
    - `error` (`object`, required)
- `500` (`application/json`): An unexpected internal error occurred.
  - Type: `object`
  - Properties:
    - `error` (`object`, required)

## Authentication

- `bearerAuth` — http (bearer) — All /v1 endpoints (except `/v1/openapi.json` and `/v1/llms.txt`) require a bearer token. Two equal first-class paths: (1) an OAuth 2.0 access token from the au…

## Useful links

- Interactive page: https://www.agencytitan.com/docs/tag/custom-object-links/POST/v1/custom-object-links
- API reference home: https://www.agencytitan.com/docs/
- Tag page: https://www.agencytitan.com/docs/tag/custom-object-links.md
- This operation as Markdown: https://www.agencytitan.com/docs/tag/custom-object-links/POST/v1/custom-object-links.md
- OpenAPI JSON: https://www.agencytitan.com/docs/openapi.json
- Full API Markdown: https://api.agencytitan.com/v1/llms.txt
- API keys: https://app.agencytitan.com/settings/api-mcp