# Writer Persona

> A Claude Code skill that extracts your writing persona from real messages, measures its accuracy, and writes in your voice.

- **Type:** MCP server
- **Install:** `agentstack add mcp-cosmos-makers-writer-persona`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [cosmos-makers](https://agentstack.voostack.com/s/cosmos-makers)
- **Installs:** 0
- **Category:** [AI & ML](https://agentstack.voostack.com/c/ai-and-ml)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [cosmos-makers](https://github.com/cosmos-makers)
- **Source:** https://github.com/cosmos-makers/writer-persona

## Install

```sh
agentstack add mcp-cosmos-makers-writer-persona
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# writer-persona

A [Claude Code](https://docs.anthropic.com/en/docs/claude-code) plugin that extracts your writing persona from real messages, measures its accuracy, and writes in your voice.

## The Problem

You want AI to write as you — in emails, Slack, code reviews. But how close is "close enough"? Without measurement, you're guessing.

## The Solution

**writer-persona** creates a feedback loop: extract, measure, improve, write.

```
Bootstrap (analyze 100+ real messages)
    ↓
Backtest (AI writes drafts → compare with what you actually wrote)
    ↓
Score (8-axis linguistic evaluation)
    ↓
Auto-correct (fix the biggest gaps)
    ↓
Write (generate messages in your voice)
```

The AI never sees your actual response when generating drafts — it only gets the conversation context. This information isolation ensures honest evaluation.

## Commands

| Command | What it does |
|---------|-------------|
| `/writer-persona:writer-persona` | Show persona status and score |
| `/writer-persona:writer-persona --bootstrap` | Extract persona from 100+ real messages |
| `/writer-persona:writer-persona --backtest` | Measure accuracy (last 24h by default) |
| `/writer-persona:writer-persona --backtest --days 7` | Measure over last 7 days |
| `/writer-persona:writer-persona --calibrate` | Manual tuning with your feedback |
| `/writer-persona:writer-persona --write "context"` | Write as you in a given situation |
| `/writer-persona:writer-persona --write` | Interactive: describe the situation, get a draft |

> **Note**: When installed as a plugin, commands use the `plugin-name:skill-name` format.
> If installed as a local skill (in `.claude/skills/`), use `/writer-persona` directly.

## Key Features

- **8-axis evaluation** grounded in computational stylometry research
- **Self-similarity ceiling** — your own writing varies; the AI is scored against *your* natural range, not perfection
- **Data source agnostic** — Slack, email, Discord, text files, or any MCP tool
- **Language adaptive** — English, Korean, Japanese, or any language
- **Auto-convergence** with overfitting guards (max 2 axes per run, stall detection)
- **Write mode** — the payoff: generate messages that sound like you

## The 8 Axes

| Axis | Weight | What it measures |
|------|--------|-----------------|
| Semantic Fidelity | 25% | Does the draft say the right *thing*? |
| Tone / Sentiment | 20% | Does it *feel* like you? |
| Formality / Register | 15% | Right level of formal/casual? |
| Discourse Patterns | 15% | How you structure responses |
| Lexical Choice | 10% | Your characteristic vocabulary |
| Function Words | 5% | Unconscious grammatical habits |
| Sentence Structure | 5% | Length, complexity patterns |
| Formatting | 5% | Emoji, punctuation, layout |

See [`references/evaluation-rubric.md`](references/evaluation-rubric.md) for the full framework and academic citations.

## Installation

### Via Plugin Marketplace (Recommended)

If the marketplace hosting this plugin is already added:

```
/plugin install writer-persona@
```

### From GitHub

Add this repo as a marketplace source, then install:

```
/plugin marketplace add cosmos-makers/writer-persona
/plugin install writer-persona@writer-persona
```

### Local Development

Test the plugin locally without installing:

```bash
git clone https://github.com/cosmos-makers/writer-persona.git
claude --plugin-dir ./writer-persona
```

### Manual (Legacy)

Copy the plugin into your project's `.claude/plugins/` directory:

```bash
git clone https://github.com/cosmos-makers/writer-persona.git
cp -r writer-persona /path/to/your/project/.claude/plugins/writer-persona
```

## Quick Start

### 1. Extract your persona

```
/writer-persona:writer-persona --bootstrap
```

The skill asks you:
- Your name and language
- How to collect your messages (Slack MCP, paste, file, email MCP, etc.)
- Your situation categories (defaults provided)

Then it analyzes 100+ messages and builds a comprehensive writing persona.

### 2. Measure accuracy

```
/writer-persona:writer-persona --backtest
```

Finds recent conversations where you responded, generates AI drafts *without seeing your answers*, and scores them on 8 axes.

### 3. Write in your voice

```
/writer-persona:writer-persona --write "reply to Sarah's Slack message about the API deadline"
```

Or interactively:
```
/writer-persona:writer-persona --write
```
The skill asks who you're writing to, what the situation is, and generates a draft in your style.

## Supported Data Sources

writer-persona is **data source agnostic**. On first run, it asks how you want to provide messages:

| Source | How |
|--------|-----|
| **Slack** | Via MCP tools (e.g., `mcp-slack`) |
| **Email** | Via email MCP tools |
| **Discord** | Via Discord MCP tools |
| **Manual** | Paste messages or provide a file path |
| **Any MCP** | Describe the tool and query pattern |

## How Scoring Works

### Self-Similarity Ceiling

Even you don't write identically every time. A quick "lol nice" and a detailed technical explanation are both authentically you — but they'd score poorly against each other.

The **self-similarity ceiling** measures this natural variation by scoring pairs of your own messages. A typical ceiling is 70-80. This becomes the 100-point baseline.

### Information Isolation

The draft-generating agent **never sees your actual response**. It only receives your persona definition and the conversation context. This ensures the backtest measures real predictive ability, not copying.

## File Structure

```
writer-persona/
├── .claude-plugin/
│   └── plugin.json             # Plugin manifest
├── skills/
│   └── writer-persona/
│       ├── SKILL.md            # Main skill definition
│       ├── persona.template.md # Blank persona template
│       ├── references/
│       │   └── evaluation-rubric.md  # 8-axis framework + citations
│       └── examples/
│           ├── persona-english.md    # Example: English persona
│           └── persona-korean.md     # Example: Korean persona
├── README.md
└── LICENSE
```

After running, the skill creates user-specific files (gitignored):
```
skills/writer-persona/
├── persona.md                  # Your persona (personal data)
└── reports/                    # Backtest reports
```

## Academic Foundations

| Concept | Source |
|---------|--------|
| Function word stylometry | Burrows' Delta (2002) |
| Multi-axis author identification | Writeprints, Abbasi & Chen (2008) |
| Formality benchmarks | GYAFC, Rao & Tetreault (2018) |
| LLM persona consistency | PersonaGym (EMNLP 2025) |
| Semantic preservation | BERTScore, Zhang et al. (2019) |
| Self-similarity baseline | TST 3-axis evaluation standard |

## License

MIT

## Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [cosmos-makers](https://github.com/cosmos-makers)
- **Source:** [cosmos-makers/writer-persona](https://github.com/cosmos-makers/writer-persona)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/mcp-cosmos-makers-writer-persona
- Seller: https://agentstack.voostack.com/s/cosmos-makers
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.