update_task

Edit task fields, including separate Markdown description and acceptance criteria, type task or bug, or its fixed status using the current version. A stale version returns a conflict.

Workflow

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. Fields save atomically. Pass null to clear assigneeId, startDate or dueDate. Actual status changes reset statusChangedAt; unrelated edits preserve it. A stale version returns 409 without applying the edit.

Arguments

Argument	Required	Type or meaning
`taskId`	Yes	Task UUID, not its human identifier such as ENG-1.
`version`	Yes	Latest row version; stale mutations return HTTP 409.
`type`	No	task, bug
`title`	No	string
`description`	No	string
`acceptanceCriteria`	No	Independent Markdown acceptance criteria, at most 100,000 characters.
`assigneeId`	No	Active member UUID; null clears an assignment on mutation, unassigned filters unassigned tasks when listing.
`priority`	No	none, low, medium, high, urgent
`status`	No	backlog, todo, in_progress, in_review, done, wont_do
`startDate`	No	Optional calendar date YYYY-MM-DD; null clears it.
`dueDate`	No	Optional calendar date YYYY-MM-DD; null clears it.
`idempotencyKey`	No	One logical mutation key, reused unchanged on retries. MCP forwards it as the REST Idempotency-Key header.

Complete input schema

{
  "type": "object",
  "properties": {
    "taskId": {
      "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)$"
    },
    "version": {
      "type": "integer",
      "exclusiveMinimum": 0,
      "maximum": 9007199254740991
    },
    "type": {
      "type": "string",
      "enum": ["task", "bug"]
    },
    "title": {
      "type": "string",
      "minLength": 1,
      "maxLength": 300
    },
    "description": {
      "type": "string",
      "maxLength": 100000
    },
    "acceptanceCriteria": {
      "type": "string",
      "maxLength": 100000
    },
    "assigneeId": {
      "anyOf": [
        {
          "type": "string",
          "format": "uuid",
          "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$"
        },
        {
          "type": "null"
        }
      ]
    },
    "priority": {
      "type": "string",
      "enum": ["none", "low", "medium", "high", "urgent"]
    },
    "status": {
      "type": "string",
      "enum": ["backlog", "todo", "in_progress", "in_review", "done", "wont_do"]
    },
    "startDate": {
      "anyOf": [
        {
          "type": "string",
          "format": "date",
          "pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))$"
        },
        {
          "type": "null"
        }
      ]
    },
    "dueDate": {
      "anyOf": [
        {
          "type": "string",
          "format": "date",
          "pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))$"
        },
        {
          "type": "null"
        }
      ]
    },
    "idempotencyKey": {
      "type": "string",
      "minLength": 8,
      "maxLength": 128
    }
  },
  "required": ["taskId", "version"],
  "additionalProperties": false
}

Example call

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

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "update_task",
    "arguments": {
      "taskId": "22222222-2222-4222-8222-222222222222",
      "version": 1,
      "status": "in_review",
      "acceptanceCriteria": "- Restore completed\n- Counts match",
      "idempotencyKey": "restore-check-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.

{
  "task": {
    "id": "22222222-2222-4222-8222-222222222222",
    "boardId": "11111111-1111-4111-8111-111111111111",
    "identifier": "ENG-1",
    "title": "Verify database restore",
    "description": "Restore a recent backup into an isolated database.",
    "acceptanceCriteria": "- Restore completed\n- Counts match",
    "type": "task",
    "status": "in_review",
    "priority": "high",
    "assigneeId": "66666666-6666-4666-8666-666666666666",
    "startDate": "2027-01-18",
    "dueDate": "2027-01-20",
    "version": 2,
    "statusChangedAt": "2027-01-18T09:30:00.000Z",
    "createdAt": "2027-01-18T09:30:00.000Z",
    "updatedAt": "2027-01-18T09:30:00.000Z",
    "createdBy": "66666666-6666-4666-8666-666666666666"
  }
}

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API Reference

update_task

Workflow

Access and behavior

Arguments

Example call

Example result

​Workflow

​Access and behavior

​Arguments

​Example call

​Example result

​Related reference

Workflow

Access and behavior

Arguments

Example call

Example result

Related reference