---
title: Why Mixins?
description: The architectural decision behind mcwaddams's modular structure.
---

import { Aside } from '@astrojs/starlight/components';

> *"What would you say... you do here?"*

mcwaddams uses Python mixins to organize 20 tools into logical groups without creating multiple MCP servers.

## The Pattern

```python
class MCWaddamsServer(
    UniversalMixin,      # 7 cross-format tools
    WordMixin,           # 10 Word-specific tools
    ExcelMixin,          # 3 Excel-specific tools
):
    pass
```

## Benefits

1. **Single server** — One MCP configuration, not three
2. **Shared utilities** — Validation, caching, format detection
3. **Clear boundaries** — Each mixin owns its tools
4. **Easy testing** — Test mixins in isolation
5. **Simple extension** — Add PowerPoint mixin without touching Word code

<Aside type="note">
See [Architecture](/explanation/architecture/) for the full design.
</Aside>