# documents.comments.reply

Add an auditable reply to an open agreement-template comment thread. Participants and newly mentioned active organization members receive in-app notifications. Requires an idempotency key.

`POST /api/v1/accounting/documents.comments.reply`

Permissions: `accounting:read`, `accounting:write` · Roles: admin, finance · Idempotency key required

MCP tool: `accounting_documents_comments_reply`

## Fields

| Field | Type | Required | Notes |
| --- | --- | --- | --- |
| `threadId` | string (ID) | Yes | The ID of the related record. |
| `body` | string | Yes | 1–10000 characters. |
| `mentions` | array of strings |  | at most 20 items; each 1–200 characters. |
| `idempotencyKey` | string | Yes | Any unique text you generate once per intended change, so a retried request only happens once. Send it as the Idempotency-Key header instead if you prefer; if you send both they must match. 8–200 characters. |

## Example request

```bash
curl https://app.getoatmilk.com/api/v1/accounting/documents.comments.reply \
  -H "Authorization: Bearer $OATMILK_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{
  "threadId": "7f0f6c1e-1c1f-4b5e-9c8d-2f5e8e3c1a10",
  "body": "Synthetic example from the docs"
}'
```

Reference page: https://app.getoatmilk.com/docs/api/documents.comments.reply