acd-persona-generator-mcp

MCP server that generates ACD-compliant AI agent persona specifications. Not just system prompts — complete character architectures with Level 2 loop design, drift defense, and behavioral memory.

Built on Agent Character Design (ACD) — a discipline for designing AI agent personalities, behavior arcs, and interaction rhythms.

What it does

Three tools covering the full persona lifecycle:

| Tool | Input | Output | |---|---|---| | assess_level | A system prompt | ACD Level (1/2/3) + stability score + weaknesses + specific upgrade actions | | generate_persona | Requirements (role, context, constraints) | Full Level 2 persona spec: disposition profile, re-grounding schedule, behavioral memory schema, drift defense rules | | upgrade_to_level2 | Existing persona spec | Enhanced spec with added loop-shaping mechanisms |

Why this exists

Most "AI persona" tools stop at Level 1 (input shaping) — a well-written system prompt. That's fragile:

• Level 1 — system prompts. Drifts under long conversations. Breaks under stimulus. What everyone does.
• Level 2 — loop shaping. Context re-injection, behavioral memory, drift detection. What Claude's best agent systems actually use.
• Level 3 — prior shaping. Fine-tuning. Expensive, rare, not always needed.

This server helps you design at Level 2 — the level where character actually stabilizes across sessions.

Grounded in real data: Anthropic's Persona Selection Model (PSM) research shows emotional conversations accelerate drift 7.3×, while Level 2 activation capping reduces drift 60%. These numbers are baked into the drift risk assessment.

Install

npm install -g acd-persona-generator

Or run directly:

npx acd-persona-generator

MCP Client Config

For Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "acd-persona-generator": {
      "command": "npx",
      "args": ["-y", "acd-persona-generator"]
    }
  }
}

Development

npm install
npm run build       # compile TypeScript
npm test            # run test suite (8 tests)
npm run dev         # run with hot reload

Requires Node ≥ 20.

Architecture

src/
├── index.ts       # MCP server entry + tool registration
├── generator.ts   # Core persona generation logic
└── schemas.ts     # Zod schemas for all tool inputs/outputs

tests/
└── generator.test.ts   # 8 tests covering all 3 tools

Part of the ACD Ecosystem

• agent-character-design — The Field Guide + methodology spec
• acd-persona-generator-mcp (this repo) — Seed 1: persona generation
• acd-behavioral-audit-mcp (coming soon) — Seed 2: audit existing agents

License

MIT. See LICENSE.

Built by Zico Zhou. The Field Guide is at agentcharacterdesign.com (coming soon).