Add a subtask to a work item

POSThttps://<your-url>/api/v2/work-items/{work_item}/subtasks

MCP id work-items.subtasks.storeAlso on this path: GET List a work item's subtasks

Creates one checklist subtask on the work item named in the path and returns it in the detail view, with a Location header pointing at the flat item path.

Token scope: api:write:project_management
Without it: 403 insufficient-token-scope.
Permission: project_management::manage_work_items
Without it: 403 insufficient-permission.
Rate cost: 1 unit, write bucket. A write costs the same whatever view you ask for.
Also: Accepts Idempotency-Key. Never cached: private, no-store. Unknown body keys are refused, never dropped.

Both are checked, scope first. A token never does more than its user. How access is checked

Request

Example: A checklist row on a work item

curl -X POST \
  'https://<your-url>/api/v2/work-items/1/subtasks' \
  -H 'Authorization: Bearer <token>' \
  -H 'Accept: application/json' \
  -H 'Content-Type: application/json' \
  -H 'Idempotency-Key: <key>' \
  -d '{
    "title": "Wire up the SSO callback"
  }'

const response = await fetch('https://<your-url>/api/v2/work-items/1/subtasks', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer <token>',
    'Accept': 'application/json',
    'Content-Type': 'application/json',
    'Idempotency-Key': '<key>',
  },
  body: JSON.stringify({
    "title": "Wire up the SSO callback"
  }),
});

use Illuminate\Support\Facades\Http;

$response = Http::withToken('<token>')
    ->acceptJson()
    ->withHeader('Idempotency-Key', '<key>')
    ->post('https://<your-url>/api/v2/work-items/1/subtasks', [
        'title' => 'Wire up the SSO callback',
    ]);

import requests
response = requests.request(
    'POST',
    'https://<your-url>/api/v2/work-items/1/subtasks',
    headers={'Authorization': 'Bearer <token>', 'Accept': 'application/json', 'Content-Type': 'application/json', 'Idempotency-Key': '<key>'},
    json={'title': 'Wire up the SSO callback'},
)

Response

The shape of the response, with sample values.

{
  "data": {
    "id": 1,
    "work_item_id": 1,
    "title": "Wire up the SSO callback",
    "description": "<p>…</p>",
    "is_resolved": false,
    "order": 1,
    "created_at": "2026-03-04T09:15:00Z",
    "updated_at": "2026-03-04T09:15:00Z",
    "work_item": {
      "id": 1
    },
    "links": {
      "self": "https://<your-url>/api/v2/work-items/1"
    }
  }
}

{
  "type": "https://developers.plnnrly.com/api/v2/problems/idempotency-key-in-flight",
  "title": "Idempotency key in flight",
  "status": 409,
  "detail": "The original request for this Idempotency-Key is still being processed. Retry shortly.",
  "instance": "/api/v2/worklogs",
  "request_id": "01K4B7Q9YV3PZ2N8T1E6M0XR4S"
}

{
  "type": "https://developers.plnnrly.com/api/v2/problems/validation-failed",
  "title": "Validation failed",
  "status": 422,
  "detail": "3 fields failed validation.",
  "instance": "/api/v2/worklogs",
  "request_id": "01K4B7Q9YV3PZ2N8T1E6M0XR4S",
  "errors": [
    {
      "pointer": "/date",
      "code": "date_format",
      "detail": "The date does not match the format Y-m-d."
    },
    {
      "pointer": "/minutes",
      "code": "min",
      "detail": "The minutes must be at least 1."
    },
    {
      "pointer": "/description",
      "code": "required",
      "detail": "The description field is required."
    }
  ]
}

The work item comes from the path, so work_item_id is not accepted in the body and a subtask can never be moved between work items. The new subtask is appended to the end of that work item's checklist; order is not accepted, and reordering is not available through the API. There is no batch create: post one subtask per request.

Path parameters

work_iteminteger or stringRequired

The WorkItem's numeric id. Or its issue_key, matching [A-Z][A-Z0-9]*-[0-9]+.

Query parameters

Unknown parameters are refused with 400, naming the parameter.

viewstring

Which field set to render.

summarydetaildefault

Request headers

X-Request-Idstringpattern

A correlation id of your own. It is recorded in our logs next to the server's request id but never returned: the response header always carries the server's id. A value that does not match the pattern is discarded silently, never rejected.

Idempotency-Keystring≤ 255

A caller-chosen key that makes this POST safe to retry. Replaying it returns the original response with Idempotency-Replayed: true.

Request body

Unknown keys are refused with 422, naming the key.

titlestring≤ 255Required

Subtask title, as shown on the checklist row. This is the field ?q= searches.

descriptionstring or null

Optional note on the subtask. HTML from the rich editor, sanitised on read and on write. Null when the subtask is just a title.

is_resolvedboolean

Whether the subtask is ticked off.

Response 201

Returns a Subtask in the detail view.

Headers

ETag: A strong validator of exactly this representation.
Idempotency-Replayed: true when this response was replayed from a stored Idempotency-Key rather than produced by a new write.
Location: The absolute URL of the created or queued resource.
RateLimit: The IETF httpapi-ratelimit-headers form of your remaining allowance on the tightest bucket this request touched.
RateLimit-Policy: The ceiling and window of that bucket, as <limit>;w=<seconds>.
X-Request-Id: The server-generated ULID correlating this response with our logs.

Every response also carries Cache-Control, Vary, X-Content-Type-Options, X-Plnnrly-Api-Version, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset. Headers and versioning