# ExQuiddity v0.1.2 - Table of Contents > An Elixir wrapper of github.com/pzfreo/quiddity to bring feature extraction from CAD, with the geometry underneath it: rays, frames, meshes and surface samples. Wrapped via rustler. ## Pages - [ex_quiddity](readme.md) - [Why this exists](why.md) - [Roadmap](roadmap.md) ## Modules - [Quiddity.Api](Quiddity.Api.md): The engine's operations, as data — and the stubs generated from it. - [Quiddity.Mcp.Tools](Quiddity.Mcp.Tools.md): The tools the MCP server offers, and the one place a name becomes a function. - [Quiddity.Native](Quiddity.Native.md): The Rust engine: `quiddity` for what a part's features are, `haecceity` for where its surfaces are. - [Quiddity.Recognition](Quiddity.Recognition.md): What quiddity recognised in a part: its features, and what every face is. - Geometry - [Quiddity](Quiddity.md): Manufacturing features of a STEP part, and the geometry under them, from Elixir. - [Quiddity.Camera](Quiddity.Camera.md): A pinhole camera: where a sensor is, what it looks along, and how wide it sees. - [Quiddity.Face](Quiddity.Face.md): One face of a part: what kind of surface it is, how big it is, which way it faces, and what it touches. - [Quiddity.Frame](Quiddity.Frame.md): One camera frame of a part: what each pixel landed on. - [Quiddity.Part](Quiddity.Part.md): A STEP part, read once and asked about as often as you like. - Scenes - [Quiddity.Mjcf](Quiddity.Mjcf.md): A part as a MuJoCo scene: the triangles quiddity meshed, as an MJCF model. - Model Context Protocol - [Quiddity.Mcp](Quiddity.Mcp.md): A Model Context Protocol server over stdio: a STEP part, for an assistant. - Exceptions - [Quiddity.Error](Quiddity.Error.md): A refusal from the engine, with the code a caller can branch on. ## Mix Tasks - [mix quiddity.mcp](Mix.Tasks.Quiddity.Mcp.md): Runs the Model Context Protocol server: one JSON-RPC message per line on stdin, one answer per line on stdout, until stdin closes.