# CNVX Case Tools MCP

A small, local MCP server for deterministic plain-text case conversion. Give an MCP-compatible assistant a tool that changes letter case without rewriting words, calling a language model, or sending text to a remote conversion service.

Maintained by CNVX, the team behind [Title Case Converter](https://titlecaseconverter.app/).

## Tool

`convert_case(text, mode)` returns a JSON object with `text` and `mode`.

| Mode | Input | Output |
| --- | --- | --- |
| lowercase | `A Quick Guide` | `a quick guide` |
| uppercase | `A Quick Guide` | `A QUICK GUIDE` |
| inverse | `A Quick Guide` | `a qUICK gUIDE` |

Spaces, blank lines, numbers, and punctuation are retained. Unicode follows Python's `str.lower`, `str.upper`, and `str.swapcase`; some letters expand (for example, uppercase `ß` becomes `SS`). Inverse case is therefore not guaranteed to be reversible for every Unicode character.

The tool accepts up to 20,000 Unicode code points and 100 lines per call. Empty input is valid. Invalid modes or oversized input return MCP tool errors.

## Install and run

Requires Python 3.10 or newer.

```sh
python3 -m venv .venv
.venv/bin/python -m pip install -r requirements.txt
.venv/bin/python server.py
```

The server uses standard input/output for MCP messages. It has no HTTP endpoint, API key, account, or paid service requirement.

For an MCP host that supports a command-and-arguments configuration:

```json
{
  "mcpServers": {
    "cnvx-case-tools": {
      "command": "/absolute/path/to/case-tools/.venv/bin/python",
      "args": ["/absolute/path/to/case-tools/server.py"]
    }
  }
}
```

Replace both paths with the actual absolute paths on your computer.

## What this resource covers

This MCP resource implements three basic Unicode operations. It does not implement APA, Chicago, AP, or MLA title capitalization. For a visual editor with six case formats, four title-case styles, preferred spellings, and editable results, use the companion [browser tool](https://titlecaseconverter.app/).

## Privacy

The server performs conversion in the local Python process. It makes no network requests and does not write input text to files. Your MCP host may separately transmit or log tool arguments according to its own settings.

## Verification

```sh
.venv/bin/python verify.py
```

This starts the real server over stdio, initializes an MCP client, lists its tools, checks all three modes and multiline Unicode examples, and verifies error handling for invalid input.

## License

MIT. Copyright 2026 CNVX.