# five-mcp

MCP server for the [FIVE Persona Engine](https://fiveengine.dev) — an LLM persona constraint engine that generates structured JSON constraints to eliminate persona drift. Instead of describing personality in words (which LLMs interpret differently each turn), FIVE defines behavioral parameters the LLM executes as a recipe. [See how it works →](https://github.com/kiro0x/five-character-engine#the-fix-dont-let-the-llm-interpret-personality-at-all)

> **Measured:** with the constraint JSON + free harness, the demo character survived a **120-turn pressure test with zero persona breaks** (plain prompt: 8 breaks; JSON alone: 1). [Numbers, transcripts and scripts →](https://github.com/kiro0x/five-character-engine#measured-does-it-actually-hold)

**Free — no API key, no account.**

## Quick Start

### Install

```bash
pip install five-mcp
```

### Use with Claude Desktop

Add to your `claude_desktop_config.json`:

```json
{
  "mcpServers": {
    "five-character-engine": {
      "command": "five-mcp"
    }
  }
}
```

That's it — no environment variables needed.

### Use with other MCP clients

Any MCP-compatible client can connect via stdio transport:

```bash
five-mcp
```

## Tool: `generate`

Generates persona constraints via the FIVE engine.

### Parameters

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `character_name` | string | Yes | Name of the character |
| `q1` – `q4` | A / B / C / D | Yes | Personality axis choices |
| `s1` – `s4` | 1–5 | No | Style sliders (default: 3) |
| `free_text` | string | No | Free-form description |

### Response

```json
{
  "status": "ok",
  "constraint": { "..." }
}
```

## Rate limits

The API is free. To keep it available to everyone, a light per-IP limit applies: **10 requests/min, 200 requests/day**. The free host may cold-start, so the first call can take up to a minute.

## Links

- **API & Docs:** [fiveengine.dev](https://fiveengine.dev)
- **GitHub:** [github.com/kiro0x/five-mcp](https://github.com/kiro0x/five-mcp)
- **Design philosophy & examples:** [five-character-engine README](https://github.com/kiro0x/five-character-engine)
- **Measured evaluation (120-turn drift test):** [five-character-engine eval/](https://github.com/kiro0x/five-character-engine/tree/main/eval)
- **Engine repo:** [github.com/kiro0x/five-character-engine](https://github.com/kiro0x/five-character-engine)

## License

MIT

mcp-name: io.github.kiro0x/five-mcp