prompt-templates-mcp

Prompt Templates MCP Server

A Model Context Protocol (MCP) server for managing prompt templates with dynamic variable substitution. This server provides tools for saving, updating, retrieving, and managing reusable prompt templates with automatic variable extraction.

Features

• Dynamic Variable Extraction: Automatically detects {variable} placeholders in templates
• MCP Tools: Full set of tools for template management accessible via MCP clients
• REST API: HTTP endpoints for integration with external applications
• Persistent Storage: Uses Cloudflare D1 database for reliable storage
• Variable Substitution: Render templates with provided input values

MCP Tools

The server exposes the following MCP tools:

1. save_prompt_template - Save new templates with automatic input extraction
2. update_prompt_template - Modify existing templates
3. delete_prompt_template - Remove templates
4. list_prompt_templates - View all saved templates
5. get_prompt_by_name - Retrieve and render templates with input values

Example Usage

// Save a template
await save_prompt_template({
  name: "greeting",
  template: "Hello my name is {firstName} {lastName}. What is my name?"
});
// Automatically extracts: firstName, lastName as required inputs

// Use the template
await get_prompt_by_name({
  name: "greeting",
  inputs: {
    firstName: "John",
    lastName: "Doe"
  }
});
// Returns: "Hello my name is John Doe. What is my name?"

REST API Endpoints

• GET /prompts - List all templates
• GET /prompts/:name - Get a specific template
• POST /prompts - Create a new template
• PUT /prompts/:name - Update a template
• DELETE /prompts/:name - Delete a template

Getting Started

This project uses the HONC stack (Hono + Cloudflare) with D1 database for storage.

Project Structure

├── src
│   ├── index.ts          # MCP server & API endpoints
│   └── db
│       └── schema.ts     # Database schema for prompt templates
├── wrangler.toml         # Cloudflare Workers configuration
├── drizzle.config.ts     # Drizzle ORM configuration
├── package.json
└── tsconfig.json

Local Development

Run the migrations and (optionally) seed the database:

# this is a convenience script that runs db:touch, db:generate, db:migrate, and db:seed
npm run db:setup

Run the development server:

npm run dev

As you iterate on the database schema, you'll need to generate a new migration file and apply it like so:

npm run db:generate
npm run db:migrate

Deployment

Before deploying your worker to Cloudflare, ensure that you have a running D1 instance on Cloudflare to connect your worker to.

You can create a D1 instance by navigating to the Workers & Pages section and selecting D1 SQL Database.

Alternatively, you can create a D1 instance using the CLI:

npx wrangler d1 create <database-name>

After creating the database, update the wrangler.toml file with the database id.

[[d1_databases]]
binding = "DB"
database_name = "honc-d1-database"
database_id = "<database-id-you-just-created>"
migrations_dir = "drizzle/migrations"

Include the following information in a .prod.vars file:

CLOUDFLARE_D1_TOKEN="" # An API token with D1 edit permissions. You can create API tokens from your Cloudflare profile
CLOUDFLARE_ACCOUNT_ID="" # Find your Account id on the Workers & Pages overview (upper right)
CLOUDFLARE_DATABASE_ID="" # Find the database ID under workers & pages under D1 SQL Database and by selecting the created database

If you haven’t generated the latest migration files yet, run:

npm run db:generate

Afterwards, run the migration script for production:

npm run db:migrate:prod

Change the name of the project in wrangler.toml to something appropriate for your project:

name = "prompt-templates-mcp"

Finally, deploy your worker:

npm run deploy

Database Schema

The server uses a simple schema to store prompt templates:

promptTemplates {
  id: integer (primary key)
  name: text (unique)
  template: text
  inputs: text (JSON array of required variables)
  createdAt: text
  updatedAt: text
}

Setting up the MCP Server in Claude Desktop

After deploying your server, follow these steps to connect it to Claude Desktop:

1. Open Claude Desktop Configuration

   • On macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
   • On Windows: %APPDATA%\Claude\claude_desktop_config.json

2. Add your MCP server to the configuration file:

{
  "mcpServers": {
    "prompt-templates": {
      "command": "npx",
      "args": [
        "@modelcontextprotocol/server-fetch",
        "https://YOUR-WORKER-URL/mcp"
      ]
    }
  }
}

Replace YOUR-WORKER-URL with your deployed Cloudflare Worker URL.

3. Restart Claude Desktop completely (quit and reopen the application)

4. Verify the connection by looking for the 🔌 icon in Claude Desktop, which indicates MCP servers are connected

Testing Your MCP Server

Once connected, you can use these tools in your conversations:

Save a template:

Use the save_prompt_template tool to save this template:
- Name: "greeting"
- Description: "A personalized greeting template"
- Template: "Hello my name is {firstName} {lastName}. What is my name?"

List your templates:

Use the list_prompt_templates tool to show me all saved templates

Use a template:

Use the get_prompt_by_name tool with:
- Name: "greeting"
- Inputs: {"firstName": "John", "lastName": "Doe"}

The server will automatically extract variables from any template you save (like {firstName} and {lastName} from your example) and make them available as structured inputs.

Built With

• Hono - Web framework
• Cloudflare Workers - Serverless platform
• Cloudflare D1 - SQLite database
• Drizzle ORM - TypeScript ORM
• Model Context Protocol - AI tool integration protocol