Your yeti
Create a yeti and shape its persona, model and look, including what it always checks with you about first.
A yeti is one of your AI agents. Each one has a name and a role, a persona that sets how it thinks and talks, a model it thinks with, a cube it prefers to run on, and a look you design in Studio.
Your first yeti
Every cluster starts with Tilly, the "Everyday helper" and your default yeti. New chats start with the default yeti. You always have at least one yeti: the last one can't be deleted.
Create a yeti
- Open Agents and choose New agent.
- Give it a Name and, if you like, a Role such as "Research buddy".
- Choose Create yeti.
A new yeti starts with no personality traits, the Just right tone, everything on the "Always check with me before…" list switched on, and Claude Opus 5.5 as its model. Shape it next, then design its look in Studio.
Persona
Pick a yeti on the Agents page to edit its persona.
| Setting | What it does | Limit |
|---|---|---|
| Name | What you call it | 40 characters |
| Role | A short job title shown under its name | 80 characters |
| Personality | Warm, Bubbly, Calm, Witty, Sassy, Precise, Curious, Dramatic | Up to 3 |
| Tone of voice | How much it says: Short & sweet, Just right, Tell me everything | One |
| Custom instructions | Read before every chat. Write it like you're describing a friend: what they're great at, how they talk, and anything they should never do | 8,000 characters |
| Sounds like | A sample line in its voice, shown in previews | 280 characters |
| Always check with me before… | Sending messages, Deleting things, Spending money, Sharing files | Any |
Picking a fourth trait replaces the one you picked first.
Draft it for me fills in Custom instructions from the name, role, traits, tone and "check with me" list. It's a template filled in on your computer, not a model call, so edit it as much as you like.
Always check with me before…
This list is your yeti's safety catch. When something it's doing would send a message, delete something, spend money or share a file, and that item is on its list, your yeti stops and asks you first.
Tilly ships with Sending messages, Deleting things and Spending money switched on. New yeti start with all four.
Model and cube
The Model and cube section sets what a yeti thinks with and where it runs.
- Provider: Claude or OpenAI.
- Model: for Claude, one of Claude Opus 5.5 (the default), Claude Sonnet 5.5, Claude Haiku 5.5 or Claude Fable 5.1. For OpenAI, type the Model ID (letters, digits and
. _ : / -, up to 100 characters). - Preferred cube: Any cube, or one of your cubes by name. This is where the yeti runs when it can.
- Default yeti: new chats start with the default yeti. There is always exactly one; to change it, switch this on for another yeti.
Each provider needs your API key. See Models and keys.
Save, discard, delete
- Save changes writes the yeti to your cluster, and every cube gets the new version. Discard puts back what was saved.
- If the same yeti was changed on another device since you opened it, saving stops with "this yeti was changed somewhere else; reload and try again" instead of overwriting it.
- Delete removes the yeti's persona and look from every cube. It can't be undone. If it was your default yeti, another one becomes the default. Your only yeti can't be deleted.
Design its look in Studio
Studio opens on your default yeti. If you have more than one, pick which yeti to edit at the top. The preview shows the look at every size the app uses.
| Tab | Choices |
|---|---|
| Horns | None, Classic, Nubs, Curly, Unicorn, Antlers, Swept, Twin spikes, Trio, Chipped, Sprout, Bunny ears. Horn size. Horn color: Frost, Snow, Ink, Ember, Blush, Glacier, Lichen |
| Face | Happy, Joy, Wink, Sleepy, Focused, Surprised, Love, Starry, Smug, Teary, Blep, Thinking. Face size |
| Accessories | Head: Beanie, Bow, Party hat, Crown, Flower, Wizard hat, Halo, Cap. Eyes: Round glasses, Sunglasses, Monocle, Ski goggles. Ears: Headphones, Earmuffs, Headset. Neck: Scarf, Bow tie, Bandana, Bell collar. Accessory size and color |
| Fur & body | Fluffy, Cloud, Shaggy, Smooth. Fur color: Snow, Frost, Blush, Peach, Mint, Glacier. Size and Squish |
| Tile | Squircle, Circle, No tile. Tile color: Yeti Blue, Glacier, Ink, Frost, Ember, Blush |
Surprise me rolls a random look and keeps your sizes. Undo changes goes back to the saved look. Save look saves it everywhere. If you switch to another yeti with unsaved changes, Studio asks before dropping them.
Chatting with your yeti
Choose New chat in the sidebar to start with your default yeti, or pick any yeti under Your yeti. Each yeti brings its own persona to the conversation: it reads its custom instructions first, sticks to its tone, thinks with the model you chose, and checks with you before anything on its list.
Where your yeti are kept
Each yeti is one document in your cluster's replicated store, copied to every cube. It holds the persona, look, model choice and preferred cube, and never any credentials: API keys live separately as sealed secrets. The documents themselves are not encrypted on the cubes' disks; Security explains what is.
If this computer's cube can't be reached, Agents and Studio show Tilly as shipped so you can look around, but nothing saves until the cube is back.