Add dictionary word in the user's own Grammarly account from ChatGPT, Claude or any AI agent. Returns how to do it in Grammarly step by step (screens, buttons, fields) and opens nothing by itself; then do it with the cotlet_browser_* tools in the user's Grammarly Cloud Browser. Grammarly's official API: Grammarly has an official API only for organizations (checked 5 Nov 2026): Writing Score, AI Detection and Plagiarism Detection, plus Analytics and License Management, reached through Contact Sales and OAuth 2.0 credentials.