---
title: "Call desk.build_card"
method: POST
path: "/api/v1/tools/desk.build_card"
tags: ["desk"]
---

# Call desk.build_card

`POST /api/v1/tools/desk.build_card`

## Request

- Base URL: `https://app.goosybear.ai`
- URL: `https://app.goosybear.ai/api/v1/tools/desk.build_card`
- Auth: HTTP bearer

Write a small custom card for this workspace — 'build me a calculator for this', 'make a countdown to the launch' — a little self-contained page, coded from the brief you give it, rendered in a sandbox and readable at its own address. Use it when what is wanted is not one of the ordinary elements: a bespoke view, a calculator, a countdown, a table shaped a particular way. Carry the operator's own sentence into brief; it is the whole instruction the card is written from. If the card needs live data, pass every Data table it may read in data_table_ids — a table you do not pass is a table the card can never see. This runs a PAID authoring session, so it answers in two calls on every key: without confirmation_id it describes what would be built, charges nothing and returns a confirmation_id; the same call again with that confirmation_id, on a member's own API key, builds it. Not for putting the card on a desk or project — that is `work.file`, with the card_id it answers as a widget's item_id.

Every result names the workspace it ran in. Say which workspace the answer is about. When the account has more than one workspace and none is selected, this tool refuses with `workspace_ambiguous` and lists the choices — offer them, never pick one.

## Headers

- `x-request-id` string

## Request body

- object
  - `title` string, required: What to call the card — its label on the desk.
  - `brief` string, required: What the card should show, in the member's own words.
  - `data_table_ids` string[]: Every Data table this card may read, and the only ones. Leave it out for a card that reads nothing.
  - `confirmation_id` string, uuid: Omit to propose: the first call says what would happen, returns a confirmation_id and changes nothing. To go ahead, send the same arguments again with that confirmation_id, on a member's own API key; a service account's key can propose but never confirm.
  - `workspace` string: Which workspace to run in — its slug. Omit to use your default. With more than one reachable workspace and no default, the call is refused and the choices are listed.

## Response `200`

The call was admitted and dispatched. `ok` says whether the tool succeeded — a refusal the tool itself produced is still a 200, exactly as it is a successful JSON-RPC result over MCP.

- union
  - object: The tool ran and answered.
    - `ok` true, required
    - `state` union, required
      - 'confirmation_required'
      - 'built': built — the card exists. (The first call answers confirmation_required: nothing was written and nothing was charged.)
    - `confirmation_id` string, uuid
    - `expires_in_seconds` integer
    - `request_summary` string: What will happen, in one sentence, for a person to approve before confirming.
    - `title` string, required: What the card is called.
    - `card_id` string, uuid: Present once built — the card's durable identity.
    - `revision` string: Present once built — the build this card is now on.
    - `entry` string: Bundle-relative path of the document the frame loads.
    - `file_count` integer
    - `bytes` integer
    - `reads` string[]: What this build declared it may read, and the only ones.
    - `door_url` string, nullable: Present once built — a short-lived address that renders this card. Null when one could not be signed for this environment; the card is still built. Treat it as a secret: it is a bearer capability and it expires.
    - `workspace` string, required: The slug of the workspace this call ran in.
    - `working_in` object, required: Which workspace this call ran in, and how that was decided. Present on every workspace-scoped result.
      - `label` string, required: The chip words — e.g. "working in: Acme Main".
      - `note` string, required: Why this workspace — e.g. "your default", "this call only".
      - `workspace` string, required: The resolved workspace's slug.
      - `source` 'call-override' | 'key-pin' | 'stored-default' | 'sole-reachable', required: Which rung of the R7 precedence resolved the workspace.
  - ToolRefusal: A call that was admitted and dispatched, and did not succeed.
    - `ok` false, required
    - `code` string, required: The typed reason — e.g. `workspace_ambiguous`, `invalid_arguments`, or the tool's own failure code.
    - `message` string, required: A sentence a person can act on.
    - `workspaces` string[]: On a workspace refusal: the slugs this key may pass as `workspace`.
    - `issues` object[]: On `invalid_arguments`: which fields failed, and why.
      - `path` string, required
      - `message` string, required
    - `path` string: On an authoring refusal: where in your call's input it points, e.g. `steps.<key>.params.<field>`.
    - `fix` string: On an authoring refusal: the change to your call that would pass.
    - `instruction` string: On an authoring refusal: what to do next with it.

## Other responses

- `400`: The request could not be used: the body is present but not a JSON object (`tenant_api.malformed_body`); it is a top-level array carrying more messages than this endpoint accepts (`tenant_mcp.batch_too_large`); or the `Idempotency-Key` header is malformed (`tenant_api.idempotency_key_invalid`), disagrees with the body's `idempotency_key` (`tenant_api.idempotency_key_conflict`), or was sent to an action that cannot replay a retry (`tenant_api.idempotency_unsupported`). Nothing ran.
- `401`: No bearer credential, or one that did not resolve. Deliberately ONE undifferentiated answer for absent / unknown / revoked / expired, so the endpoint is never an oracle over the key space.
- `403`: The credential is good but the surface is not open to it — the platform or account API switch is off, or the holder lacks the `api.access` capability. The `code` says which.
- `404`: No such tool. The body names no tool and is identical for every unrecognised name.
- `429`: Over this key's per-minute cap. Carries `Retry-After` and `error.retry_after_seconds`.

---

[API](https://skmtc.dev/goosybear/apis/goosy-bear-api.md) · [All operations](https://skmtc.dev/goosybear/apis/goosy-bear-api/llms.txt) · [OpenAPI document](https://skmtc.dev/goosybear/apis/goosy-bear-api/revisions/0e033701d3f7?raw)