# Facet

> Build a specialized model for one task, check it, and call it like any model.

Facet builds a specialized model for one narrow task, checks every change against plain-language Expectations, and serves it through an OpenAI-compatible API. Agents use it through the MCP server at https://facet.halfspacelabs.com/mcp.

## Docs

- [Overview](https://facet.halfspacelabs.com/docs/index.md): Build a specialized model for one task, check it, and call it like any model.
- [Quickstart](https://facet.halfspacelabs.com/docs/quickstart.md): Make a Task, call it from your code, and ask for it to get better.
- [Concepts](https://facet.halfspacelabs.com/docs/concepts.md): Tasks, Asks, Changes, Expectations and Versions, and how they fit together.
- [Call a Task](https://facet.halfspacelabs.com/docs/call.md): Call any Task through the OpenAI-compatible API with the OpenAI SDK.
- [Use Facet from an agent](https://facet.halfspacelabs.com/docs/agents.md): Connect any MCP client to Facet, sign in, and run the whole loop from your agent.
- [The /v1 API](https://facet.halfspacelabs.com/docs/api.md): The HTTP API behind the web app and the MCP tools.

## Optional

- [OpenAPI contract](https://facet.halfspacelabs.com/docs/openapi.yaml): every /v1 operation
- [All docs in one file](https://facet.halfspacelabs.com/llms-full.txt)