Update Document Markdown

The unique identifier for the Google Docs document to update. Accepts either a document ID (alphanumeric string, length varies by document age - newer documents typically have 44-character IDs) or a full Google Docs URL (e.g., https://docs.google.com/document/d/{DOCUMENT_ID}/edit). When a URL is provided, the document ID will be automatically extracted.

Optional tab ID to replace with the rendered Markdown. When omitted, the first tab is updated.

Markdown content that will replace the document's entire existing content. Supports standard Markdown features.