About Facet
Facet is an agent plugin for building and checking specialized models for narrow tasks, then serving them through an OpenAI-compatible API. It includes a remote MCP server and a Skill for agents that support plugins.
Key features
- 01Builds specialized models for narrow tasks
- 02Checks changes against plain-language Expectations
- 03Serves models through an OpenAI-compatible API
- 04Includes the `use-facet` Skill
Use cases
- 01Create a model for a specific task
- 02Review model changes against Expectations
- 03Call a specialized model from an agent
MCP support
Provides a remote MCP server at `https://facet.halfspacelabs.com/mcp`; MCP clients authenticate with OAuth.
Configuration
Remote servers need no local install. Pick your client, then copy the config or install in one click.
https://facet.halfspacelabs.com/mcpclaude mcp add --transport http halfspacelabs-facet https://facet.halfspacelabs.com/mcp{"mcpServers":{"halfspacelabs-facet":{"type":"http","url":"https://facet.halfspacelabs.com/mcp"}}}Open in Cursor{"servers":{"halfspacelabs-facet":{"type":"http","url":"https://facet.halfspacelabs.com/mcp"}}}Open in VS Code{"mcpServers":{"halfspacelabs-facet":{"type":"http","url":"https://facet.halfspacelabs.com/mcp"}}}{"mcpServers":{"halfspacelabs-facet":{"serverUrl":"https://facet.halfspacelabs.com/mcp"}}}Run commands in a terminal; paste JSON into the client’s MCP config and restart. Servers that need sign-in will prompt on first connect.
Tools
Details
From the project READMEFacet plugins
Facet builds a specialized model for one narrow task, checks every change against plain-language Expectations, and serves it through an OpenAI-compatible API. This repository is its agent plugin: the remote MCP server and the use-facet Skill, for every agent that takes plugins.
- Claude Code:
/plugin marketplace add halfspacelabs/facet-plugins, then/plugin install facet@facet - Cursor: install Facet from the Cursor marketplace
- Codex and ChatGPT: install Facet from the plugin directory
- Any MCP client: add
https://facet.halfspacelabs.com/mcp; it signs you in with OAuth
Docs: facet.halfspacelabs.com/docs/agents
This repository is published from plugin/ in Facet's own repository; change it there.
Comments
New to MCP?
From what the protocol is to installing your first server, these answers cover most first questions.
An open protocol that defines how AI applications connect to external tools and data in a uniform way. Clients talk to the model; MCP servers provide tools, resources and prompt templates. They exchange standard messages, so one server can be reused by many clients.