# MCP for coding agents

> mixel mcp gives Claude Code, Cursor and other agents the whole build loop as small tools, so they check their own work.

`mixel mcp` is a local [MCP](https://modelcontextprotocol.io) server. It runs on your computer over stdio, needs no account, and reads and writes app folders through the same code as the `mixel` command. An agent that uses it gets error codes with one-line fixes instead of reading docs, which keeps it fast and its context small.

## Add it to your agent

**Claude Code**
```sh
claude mcp add mixel -- mixel mcp
```

**Cursor**
Add this to `.cursor/mcp.json` in your project, or to `~/.cursor/mcp.json` for every project:

```json
{ "mcpServers": { "mixel": { "command": "mixel", "args": ["mcp"] } } }
```

**Other agents**
Any MCP client works. The server is the command `mixel` with the argument `mcp`, over stdio.

## What the agent can do

| Tool | Does |
| --- | --- |
| `start` | The rules in short, and what to call next. Agents call it first. |
| `app_new` | Creates an app folder that checks clean, with a test |
| `app_check` | The checks Mixel and reviewers apply. `fix: true` adds missing permissions. |
| `app_describe` | What Mixel will see: each action's input and the permissions |
| `app_run` | Runs one action on real files, and returns the result and a log tail |
| `app_test` | Checks, then runs `tests/`, and returns only the failures |
| `docs_search`, `docs_read` | Finds and reads one section of these docs |
| `ui_components` | The design-system components and tokens for a page |
| `app_status` | Review state and reviewer notes, after `mixel login` |
| `library_overview`, `library_search`, `propose_crate` | Your own Library, as [your AI assistant](https://docs.0x1audio.com/assistant.md) sees it. Off unless you turn it on in Mixel. Needs `mixel` 0.3.5 or later. |

AGENTS.md, each docs page and each error code are also there as resources (`mixel://agents.md`, `mixel://docs/{slug}`, `mixel://errors/{code}`).

## What it won't do

It never publishes. Sending an app for review stays your decision, with `mixel publish` in your terminal. `mixel mcp --read-only` offers only the tools that change nothing.

## A good first prompt

> Build a Mixel app in this folder that slices a song into equal pieces for a sampler. Use the mixel MCP tools: call start first, and keep calling app_check until it has no errors.

The [15-minute tutorial](https://docs.0x1audio.com/tutorial.md) goes from there to a submitted app.