> ## Documentation Index
> Fetch the complete documentation index at: https://www.mill.fyi/llms.txt
> Use this file to discover all available pages before exploring further.

# update_board

> Update a board with Mill MCP.

Edit board settings. Prefixes must be unique; changing one renames existing task identifiers while preserving task numbers and links. Send the current version to protect concurrent edits.

## Workflow

```mermaid theme={"system"}
flowchart LR
  step0["Read current board version"] --> step1
  step1["Choose an available prefix"] --> step2
  step2["Save and refresh task identifiers"]
```

## Access and behavior

Write or Administrator OAuth consent and a member/administrator team role are required. Tools are listed and callable only when the current grant and role permit them.

A prefix change atomically renames existing task identifiers while preserving task numbers and UUID links. Existing task versions increase. Duplicate prefixes return 409 `BOARD_PREFIX_TAKEN`; stale versions conflict. Omitted fields remain unchanged.

## Arguments

| Argument | Required | Type or meaning |
| - | - | - |
| `boardId` | Yes | Board UUID, not its task prefix. |
| `version` | Yes | Latest row version; stale mutations return HTTP 409. |
| `name` | No | string |
| `description` | No | string |
| `prefix` | No | string |
| `idempotencyKey` | No | One logical mutation key, reused unchanged on retries. MCP forwards it as the REST Idempotency-Key header. |

> **Complete input schema**
>
> ```json theme={"system"}
> {
>   "type": "object",
>   "properties": {
>     "boardId": {
>       "type": "string",
>       "format": "uuid",
>       "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$"
>     },
>     "version": {
>       "type": "integer",
>       "exclusiveMinimum": 0,
>       "maximum": 9007199254740991
>     },
>     "name": {
>       "type": "string",
>       "minLength": 1,
>       "maxLength": 100
>     },
>     "description": {
>       "type": "string",
>       "maxLength": 10000
>     },
>     "prefix": {
>       "type": "string",
>       "pattern": "^[A-Z][A-Z0-9]{1,9}$"
>     },
>     "idempotencyKey": {
>       "type": "string",
>       "minLength": 8,
>       "maxLength": 128
>     }
>   },
>   "required": ["boardId", "version"],
>   "additionalProperties": false
> }
> ```

## Example call

The client initializes the MCP connection before sending this JSON-RPC call. Example records are fictional.

```json theme={"system"}
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "update_board",
    "arguments": {
      "boardId": "11111111-1111-4111-8111-111111111111",
      "version": 1,
      "prefix": "OPS",
      "idempotencyKey": "engineering-prefix-edit-001"
    }
  }
}
```

## Example result

Mill returns this object in `structuredContent` and normally a JSON text content block (large responses may shorten the text block). A tool failure sets `isError`; never treat an error as a completed mutation.

```json theme={"system"}
{
  "board": {
    "id": "11111111-1111-4111-8111-111111111111",
    "workspaceId": "55555555-5555-4555-8555-555555555555",
    "name": "Engineering",
    "prefix": "OPS",
    "description": "Track delivery and reliability.",
    "version": 2,
    "nextNumber": 2,
    "createdAt": "2027-01-18T09:30:00.000Z",
    "updatedAt": "2027-01-18T09:30:00.000Z",
    "createdByUserId": "66666666-6666-4666-8666-666666666666",
    "createdByName": "Alex Morgan",
    "createdByKind": "human",
    "lastActivityAt": "2027-01-18T09:30:00.000Z"
  }
}
```

## Related reference

[HTTP operation](https://www.mill.fyi/api-reference/patch_api_boards_by_boardId.md) · [Connect an MCP client](https://www.mill.fyi/mcp-connections.md) · [Request conventions](https://www.mill.fyi/api-reference/overview.md)


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