| Filename | Latest commit message | Latest commit date |
|---|---|---|
* docs: add local development MCP client configuration to READMEs Add instructions for configuring MCP clients to use locally-cloned and modified servers. This allows developers to test local changes with MCP clients like Claude Desktop or VS Code. - Top-level README: Added 'Local Development' section after npx config - All TypeScript examples: Added 'Local Development' subsection with bash one-liner that builds and runs the server - Python examples (qr-server, say-server): Added local path config * docs: include all servers in local development config * docs: use bash wrapper for Python server configs to enable tilde expansion |
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| .. | ||
| src | ||
| .gitignore | ||
| grid-cell.png | ||
| main.ts | ||
| mcp-app.html | ||
| package.json | ||
| README.md | ||
| screenshot.png | ||
| server.ts | ||
| tsconfig.json | ||
| tsconfig.server.json | ||
| vite.config.ts | ||
Example: Cohort Heatmap App
A demo MCP App that displays cohort retention data as an interactive heatmap, showing customer retention over time by signup month.
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MCP Client Configuration
Add to your MCP client configuration (stdio transport):
{
"mcpServers": {
"cohort-heatmap": {
"command": "npx",
"args": [
"-y",
"--silent",
"--registry=https://registry.npmjs.org/",
"@modelcontextprotocol/server-cohort-heatmap",
"--stdio"
]
}
}
}
Local Development
To test local modifications, use this configuration (replace ~/code/ext-apps with your clone path):
{
"mcpServers": {
"cohort-heatmap": {
"command": "bash",
"args": ["-c", "cd ~/code/ext-apps/examples/cohort-heatmap-server && npm run build >&2 && node dist/index.js --stdio"]
}
}
}
Features
- Cohort Retention Heatmap: Color-coded grid showing retention percentages across cohorts and time periods
- Multiple Metrics: Switch between Retention %, Revenue Retention, and Active Users
- Period Types: View data by monthly or weekly intervals
- Interactive Exploration: Hover cells for detailed tooltips, click to highlight rows/columns
- Color Scale: Green (high retention) through yellow to red (low retention)
- Theme Support: Adapts to light/dark mode preferences
Running
-
Install dependencies:
npm install -
Build and start the server:
npm run start:http # for Streamable HTTP transport # OR npm run start:stdio # for stdio transport -
View using the
basic-hostexample or another MCP Apps-compatible host.
Architecture
Server (server.ts)
Exposes a single get-cohort-data tool that returns:
- Cohort rows with signup month, original user count, and retention cells
- Period headers and labels
- Configurable parameters: metric type, period type, cohort count, max periods
The tool generates synthetic cohort data using an exponential decay model with configurable retention curves per metric type.
App (src/mcp-app.tsx)
- Uses React for the heatmap visualization
- Fetches data on mount and when filters change
- Displays retention percentages in a grid with HSL color interpolation
- Shows detailed tooltips on hover with user counts and exact retention values
- Supports row/column highlighting on cell click


