Each answer stands on its own. For setup steps and reference, see the Facet docs.
What Facet is
What is Facet?
Facet, made by Halfspace, builds a specialist for one task you describe, such as routing support tickets or pulling fields out of invoices. The specialist does that one job faster and at lower cost than a frontier model, you call it with the OpenAI SDK, and it improves each time you correct it.
What kinds of tasks is Facet for?
Facet is for narrow text jobs that run often, such as routing tickets, extracting fields, sorting text into categories, redacting personal data, rewriting in a house style, or grading text against your rules. Facet handles text today.
Do I need to write prompts or prepare examples for Facet?
No. A few real inputs help, but Facet writes the instructions and the examples itself. You describe the job and agree on what a good answer looks like, and you can open and edit anything Facet wrote.
Can my AI agent use Facet?
Yes. Facet has an MCP server at https://facet.halfspacelabs.com/mcp that works with Claude, Cursor, ChatGPT, Codex and VS Code, so your agent can build a specialist, ask for fixes and call it, while you approve anything that costs money.
Quality
How does Facet know a specialist is good enough?
Facet checks every version against plain statements of what a good answer does, each with examples, and keeps some examples hidden so only the checks see them. A new version goes live only when it passes.
What happens when a specialist gets something wrong?
You say what should change, in plain words. Facet turns it into a new check, measures how often the current version misses it, and quotes the fix; nothing is spent until you approve, and any update rolls back in one step.
Cost
Can a Facet bill surprise me?
No. Every build shows its price before it starts, and that price is a cap it never goes past. A monthly spending limit, on by default, stops new work and calls when it's reached; Facet emails your workspace's Owners as spend nears it, and an Owner can raise it.
Data and ownership
Does Facet store what my app sends to a specialist?
Facet's own systems keep only each call's details, such as which version answered, token counts and response time, never the inputs or the answers. Our GPU provider holds each call for up to 7 days to run it, then deletes it. Examples you add while building a specialist stay in your workspace until you delete them.
Do other AI services see my data while Facet builds a specialist?
Only to build and check it. Facet writes practice examples and checks answers with open-weight models, through hosts that keep nothing once they answer, and Facet's own agent runs on Anthropic's Claude. The Halfspace privacy policy lists every service and what it sees.
Does Facet use my data to train models for anyone else?
No. Facet uses what you put in only to build, check and run your own specialists, and never sells it.
Can I take my specialist out of Facet?
Yes. Export it any time, free, with its model files and instructions in a standard open format, and run it on your own servers.