AI tells are the habits that make text read as machine-written, and no single one proves anything. This checklist covers the nine that matter most, what Wikipedia's "Signs of AI writing" guide says (including why em dashes are now an older tell), tells in fiction, a two-minute scan to run before you publish, and an honest answer to whether people can tell you use AI.

How to write a viral Twitter thread in 2026 means retiring most of what worked from 2020 to 2023: the 1/n emoji, the numbered-framework hook, the beige bullet middle, the save-retweet-follow close. The 2026 shape is a hook that earns the click, an uneven payload, no interchangeable bullets and a close that doesn't pitch. This guide also revisits the six classic Twitter writing tips and shows which ones still hold up.

To use AI for tweet writing without losing your voice, keep the AI in the ideation, outline, and editing roles and never let it write the post from a blank prompt. Bring your own idea, generate options and rewrite aggressively, check your cumulative output for drift weekly, and reach for a voice-trained tool (with a Style and Stance check) once you are posting at volume. The working playbook, the prompts that help, and the drift test.