# Feature Doc Entity
### Scope
- **Purpose**: Document what `derive_tools` does and why it exists as a unified facade.
- **Responsibility**: Master index for all feature doc instances in this crate.
- **In Scope**: Instance 001 — aggregate facade over workspace and external derive macros.
- **Out of Scope**: Public interface contracts — see `api/` instances.
### Overview Table
| 001 | [Aggregate Facade](001_aggregate_facade.md) | Unified facade aggregating workspace and external derive macros | ✅ |