five-mcp

MCP server for the FIVE Persona Engine — 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 →

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 →

Free — no API key, no account.

Quick Start

Install

pip install five-mcp

Use with Claude Desktop

Add to your claude_desktop_config.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:

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

{
  "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

License

MIT

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