Which model to use

The assistant runs on a Metis model on your Mac, or on a hosted model. An agent outside the app takes the same role over MCP. Every one of them has the same tools, so the choice is about cost, privacy, speed, and the size of the job.

Option	Cost	Your photos	Best for
A local Metis model	Nothing per request	Stay on your Mac	Straightforward edits
A hosted model	Per request	A downsampled copy goes to the provider	The best result on a hard request
An agent over MCP	A subscription, or per request	A downsampled or exported copy goes to the agent’s provider	Work with your other software

You can change the choice at any time in the settings. See Set up the assistant.

A local Metis model

A Metis model costs nothing per request and needs no account. Nothing about your photos leaves the app. The cost is disk space, memory, and a slower turn than a large hosted model gives. Every Metis model is small compared to a hosted model, so on a hard request the hosted model gives the better answer.

Which Metis model

Start with the model that matches how you work. The three models divide by the kind of request they answer.

Model	Answers	Example prompt	Use it for
Metis Micro	An explicit change.	“shadows up, highlights down”	Precise edits that you make one after another.
Metis Small	An open-ended prompt.	“fix the tones”	A less precise edit, where a “good enough” result is what you want. Tags for a photo.
Metis Large	A request about style.	“make it look shot on Velvia 50”	Exploratory work, if the Mac has the memory for it.

Metis Micro works best with the control names, or with words close to them. See Control keys and ranges.

Metis Small edits conservatively, so ask for more than you think you need.

Metis Large often gives a better result for the same prompt. A request about style takes it a few rounds, so do not expect the look in one shot. For a precise request, use Metis Micro. For a complicated request, use a hosted model. Metis Large crops better than the other two, and a manual crop is still better than any of them.

See Local Metis models for the hardware requirements of each model.

A hosted model

A hosted model runs on hardware your Mac does not have. Opus 5 from Anthropic, Terra and Sol from OpenAI, and Kimi K3 are examples. Providers release new models often, so check what the provider offers today. The more capable the model, the better it drives the assistant.

A provider bills you per request and needs an account and an API key. The request and a downsampled copy of the photo leave your Mac, so the provider sees the work.

Note

A hosted model charges for every token it uses. Fotometis keeps its requests as small as it can, and you pay for the requests it makes. One edit with Kimi K3 on OpenRouter costs 5 to 20 cents. Your own requests can cost more or less.

A hosted model suits exploration: it offers directions you did not consider. It reads composition, lighting, and photographic technique better than a Metis model does. Use one where the result is worth the cost.

An agent over MCP

An agent may use the same hosted models. The agent app decides which models are available, and you pick the model there instead of in Fotometis.

For what an agent adds and what it costs, see When to use an agent. For the steps, see Connect an MCP client and Tag photos in bulk.