eyaltoledano/claude-task-master · error

INPUT_VALIDATION_ERROR

INPUT_VALIDATION_ERROR

Error message

Parent task ID is required

What it means

addSubtaskDirect validates that id — the parent task under which the subtask will be added — is provided. A missing id returns a structured INPUT_VALIDATION_ERROR result. Without a parent task the core function cannot decide where to insert the new subtask.

Source

Thrown at mcp-server/src/core/direct-functions/add-subtask.js:62

		log.info(`Adding subtask with args: ${JSON.stringify(args)}`);

		// Check if tasksJsonPath was provided
		if (!tasksJsonPath) {
			log.error('addSubtaskDirect called without tasksJsonPath');
			return {
				success: false,
				error: {
					code: 'MISSING_ARGUMENT',
					message: 'tasksJsonPath is required'
				}
			};
		}

		if (!id) {
			return {
				success: false,
				error: {
					code: 'INPUT_VALIDATION_ERROR',
					message: 'Parent task ID is required'
				}
			};
		}

		// Either taskId or title must be provided
		if (!taskId && !title) {
			return {
				success: false,
				error: {
					code: 'INPUT_VALIDATION_ERROR',
					message: 'Either taskId or title must be provided'
				}
			};
		}

		// Use provided path
		const tasksPath = tasksJsonPath;

View on GitHub (pinned to c0c98d367c)

Solutions

1. Include id with the parent task's ID (e.g. '1' or 'HAM-12').
2. Match argument names exactly to the tool schema (id, not parentId or parent).
3. Ensure the parent task exists in tasks.json before adding the subtask.
4. If you meant to convert an existing task into a subtask, pass id (parent) plus taskId (the existing task).

Example fix

// before
await addSubtaskDirect({ tasksJsonPath, title: 'Write tests' });
// after
await addSubtaskDirect({ tasksJsonPath, id: '1', title: 'Write tests' });

function assertParentId(args) {
  const id = args?.id;
  if (typeof id !== 'string' || id.trim() === '') {
    throw new Error('Parent task ID (id) is required');
  }
  const data = JSON.parse(fs.readFileSync(args.tasksJsonPath, 'utf8'));
  if (!data.tasks?.some(t => String(t.id) === id)) {
    throw new Error(`Parent task ${id} not found in tasks.json`);
  }
}

function hasParentId(args) {
  return typeof args?.id === 'string' && args.id.trim().length > 0;
}

if (!hasParentId(args)) {
  return { success: false, error: { code: 'INPUT_VALIDATION_ERROR', message: 'Parent task ID is required' } };
}

When it happens

Trigger: Calling add_subtask with only title/taskId (creating a subtask payload) but omitting the parent id; a client sending parentId instead of id; generated tool calls dropping the first positional-style argument.

Common situations: Confusion between the parent id and the optional existing taskId (task to convert into a subtask); LLM tool calls that omit arguments they consider inferable; migrating scripts from a CLI flag spelling (--parent) to the MCP argument spelling.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• INPUT_VALIDATION_ERROR
• MISSING_ARGUMENT
• MISSING_ARGUMENT
• MISSING_ARGUMENT
• MISSING_ARGUMENT

AI-assisted analysis of eyaltoledano/claude-task-master@c0c98d367c (2026-08-29). Data as JSON: /api/errors/8df0203b023b9c0d. Report an issue: GitHub.