ext-apps/examples/scenario-modeler-server/README.md
Jonathan Hefner 4ca20f21c4
Smoothen the process of getting started (#103)
* Restructure threejs-server README to match marketing examples

- Update title format to "Example: Three.js App"
- Constrain screenshot width using table layout
- Add Features section with key capabilities
- Reorganize Running section with Tool Input subsection
- Add Architecture section describing server and app components
- Remove implementation-focused sections (WidgetProps, Creating a New Widget)

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* Add bun as devDependency to example packages

npm install now automatically installs bun, eliminating the need for
separate installation instructions. Removed manual bun install step
from customer-segmentation-server README.

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* Add start:http and start:stdio npm scripts to examples

For the 6 examples supporting --stdio transport, add explicit scripts:
- serve:http / serve:stdio for running the server
- start:http / start:stdio for build + serve
- start now aliases to start:http for backward compatibility

Update READMEs to document both transport options.

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* Default basic-host SERVERS to localhost:3001/mcp

- Change threejs-server default port from 3109 to 3001 for consistency
- Add default SERVERS value in basic-host serve.ts
- Document SERVERS env var in basic-host README

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* Improve Examples section in README

Frame the three basic examples as foundational starting points and
add a link to the examples directory for additional demo apps.

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Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
2025-12-09 16:15:32 +01:00

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Markdown

# Example: SaaS Scenario Modeler
A React-based demo MCP App that lets users adjust SaaS business parameters and see real-time 12-month projections of revenue, costs, and profitability with comparison against pre-built scenario templates.
<table>
<tr>
<td><a href="https://modelcontextprotocol.github.io/ext-apps/screenshots/scenario-modeler-server/01-compare-to.png"><img src="https://modelcontextprotocol.github.io/ext-apps/screenshots/scenario-modeler-server/01-compare-to.png" alt="Compare to" width="100%"></a></td>
<td><a href="https://modelcontextprotocol.github.io/ext-apps/screenshots/scenario-modeler-server/02-bootstrapped-growth.png"><img src="https://modelcontextprotocol.github.io/ext-apps/screenshots/scenario-modeler-server/02-bootstrapped-growth.png" alt="Bootstrapped growth" width="100%"></a></td>
<td><a href="https://modelcontextprotocol.github.io/ext-apps/screenshots/scenario-modeler-server/03-vc-rocketship.png"><img src="https://modelcontextprotocol.github.io/ext-apps/screenshots/scenario-modeler-server/03-vc-rocketship.png" alt="VC rocketship" width="100%"></a></td>
</tr>
</table>
## Features
- **Interactive Parameters**: 5 sliders for Starting MRR, Growth Rate, Churn Rate, Gross Margin, and Fixed Costs
- **12-Month Projections**: Line chart showing MRR, Gross Profit, and Net Profit over time
- **Scenario Templates**: 5 pre-built business strategies (Bootstrapped, VC Rocketship, Cash Cow, Turnaround, Efficient Growth)
- **Template Comparison**: Overlay dashed lines to compare your scenario against any template
- **Summary Metrics**: Key metrics including Ending MRR, Total Revenue, Total Profit, and break-even month
- **Theme Support**: Adapts to light/dark mode preferences
## Running
1. Install dependencies:
```bash
npm install
```
2. Build and start the server:
```bash
npm run start:http # for Streamable HTTP transport
# OR
npm run start:stdio # for stdio transport
```
3. View using the [`basic-host`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host) example or another MCP Apps-compatible host.
## Architecture
### Server (`server.ts`)
Exposes a single `get-scenario-data` tool that returns:
- 5 pre-built scenario templates with parameters, projections, and summaries
- Default input values for the sliders
- Optionally computes custom projections when `customInputs` are provided
The tool is linked to a UI resource via `_meta[RESOURCE_URI_META_KEY]`.
### App (`src/`)
- Built with React for reactive slider updates and derived state management
- Uses Chart.js for the line chart visualization
- All projection calculations run client-side for instant slider feedback
- Components: `SliderRow`, `MetricCard`, `ProjectionChart`
- Template comparison shown as dashed overlay lines on the chart