Prompt Registry: Your Personal Prompt Registry Server 🏰✍️

MCP Prompt Registry is a lightweight, file-based Model Context Protocol (MCP) prompt server designed for developers. It runs via stdio, making it perfect for local development and integration with CLIs or desktop AI assistants that support MCP. It allows you to manage your prompts in a single directory, keeping your workflow simple and portable.

✨ Features

• Single Prompt Storage Directory:
  • All prompts are stored in a single directory. You can control the location with the PROMPT_REGISTRY_PROJECT_DIR environment variable. If not set, prompts are stored in ~/.promptregistry/ in your home directory.
• File-Based: Prompts are simple JSON files – easy to read, edit, and version control.
• Standard MCP Compliance:
  • Exposes prompts via standard prompts/list (lists all prompts).
  • Allows prompts to be used via standard prompts/get (applies template variables).
  • Notifies clients of changes via notifications/prompts/list_changed.
• Management via MCP Tools:
  • add_prompt: Add new prompts.
  • get_prompt_file_content: View the raw JSON of a prompt.
  • update_prompt: Modify prompts.
  • delete_prompt: Remove prompts.
  • filter_prompts_by_tags: Discover prompts by tags.
• Stdio Interface: Communicates over standard input/output, ideal for local tools.
• Template Variables: Supports {{variable_name}} syntax in prompt content.
• Zod Schema Validation: Robust validation for tool arguments.

Prerequisites

• Node.js: Version 18 or higher.
• npm (or yarn).
• (Optional) Docker: If you want to run the server in a container.

📁 Directory Structure for Prompts

The server uses a single directory for all prompts:

1. If the environment variable PROMPT_REGISTRY_PROJECT_DIR is set, prompts are stored in that directory.
2. If not set, prompts are stored in ~/.promptregistry/ in your home directory. On first startup, or if prompts are missing, the server will attempt to copy predefined prompts from a local default_prompts_data/ directory (if present) into ~/.promptregistry/.

Prompt JSON File Structure (your-prompt-id.json):

{
  "id": "your-prompt-id",
  "description": "A brief description for MCP listing",
  "content": "Your prompt template, e.g., Explain {{concept}} like I'm {{age}}.",
  "tags": ["tag1", "category_a"],
  "variables": {
    "concept": { "description": "The concept to explain", "required": true },
    "age": { "description": "The target audience's age", "required": false }
  },
  "metadata": { "version": "1.1", "author": "You" }
}

🚀 Installation and Running

Installing via Smithery

To install Prompt Registry for Claude Desktop automatically via Smithery:

npx -y @smithery/cli install @stevengonsalvez/promptregistry-mcp --client claude

1. Using the Published NPM Package (Recommended for Clients)

If promptregistry-mcp is published to npm, clients can easily run it.

1. Ensure Node.js and npx are installed.
2. Configure your MCP client (like Claude Desktop or Amazon Q) to use it. See examples below.

2. Local/Manual Installation (For Development or Direct Use)

1. Clone the repository or download the files: (Assuming you have server.ts, package.json, tsconfig.json, and an optional default_prompts_data/ directory)

2. Install dependencies: Navigate to the server's root directory in your terminal:

   npm install
   # or
   # yarn install
   

3. Build the server (compile TypeScript):

   npm run build
   

   This will create a dist/ directory with the compiled JavaScript.

4. Run the server:

   • For development (uses tsx to run TypeScript directly, with auto-restart on changes):

     npm run dev
     

   • To run the compiled version:

     npm run start:prod
     

   The server will start listening on stdin and outputting to stdout. Console messages from the server (like "Server is running...") will appear on stderr.

   It will create the prompt directory (either as specified by PROMPT_REGISTRY_PROJECT_DIR or ~/.promptregistry/) if it doesn't exist.

3. Running with Docker

1. Build the Docker image: Ensure you have Docker installed. From the server's root directory:

   docker build -t mcp-promptregistry .
   

   (You can change mcp-promptregistry to promptregistry-mcp or your preferred image name)

2. Run the Docker container:

   docker run -i -t --rm mcp-promptregistry
   

   • -i: Keep STDIN open (interactive).

   The container will have its own internal prompt directory. To persist prompts outside the container or use existing local prompts:

   # Example: Mount local directory into the container
   docker run -i -t --rm \
     -v "$HOME/.promptregistry:/root/.promptregistry" \
     mcp-promptregistry 
   

   (Note: The home directory for the root user inside the Alpine container is /root)

🔌 Connecting with MCP Clients

Here's how you might configure clients like Claude Desktop or Amazon Q to use your MCP Prompt Registry. The exact JSON structure might vary slightly based on the client's implementation, but the core idea is to define a stdio server.

Option A: Using the (Hypothetically) Published NPM Package promptregistry-mcp

If this server were published to npm as promptregistry-mcp, the configuration would be very clean:

// Example client configuration JSON
{
  "mcpServers": {
    "mcp-promptregistry": {
      "command": "npx",
      "args": [
        "mcp-promptregistry"
      ],
      "env": {
        "PROMPT_REGISTRY_PROJECT_DIR": "/path/to/your/prompts" 
      }
    }
  }
}

This assumes promptregistry-mcp when run via npx correctly starts the stdio server.

Option B: Running from Local (Compiled) Source

If you've built the server locally and want to point your client to it:

// Example client configuration JSON
{
  "mcpServers": {
    "localPromptRegistry": {
      "command": "node", 
      "args": [
        "/full/path/to/your/mcp-promptregistry/dist/server.js"
      ],
      "env": {}
    }
  }
}

Replace /full/path/to/your/mcp-promptregistry/ with the actual absolute path to where you cloned/built the server.

Important Considerations for Client Configuration:

• Absolute Paths: When specifying paths for local commands (Option B), always use absolute paths, as the client application might execute the command from a different working directory.
• Environment Variables (env): Use PROMPT_REGISTRY_PROJECT_DIR to control where prompts are stored.
• Client-Specific Structure: The top-level key (e.g., "mcpServers") and the exact structure can vary between different MCP client applications. Adapt the command, args, and env to fit the client's requirements. The key is how it invokes your stdio server.

🧪 Testing the Server

1. Manual Stdio (JSON-RPC)

The most direct way to test. Run your server, then paste JSON-RPC messages into the same terminal and press Enter.

Example prompts/list request:

{"jsonrpc":"2.0","id":"list1","method":"prompts/list"}

The server's JSON-RPC response will appear on stdout. Server logs will appear on stderr.

Example add_prompt tool call:

{"jsonrpc":"2.0","id":"add1","method":"tools/call","params":{"name":"add_prompt","arguments":{"id":"my-test-prompt","content":"Test content: {{var1}}","tags":["test"],"variables":{"var1":{"description":"A test variable"}}}}}

2. MCP Inspector

The MCP Inspector is a GUI tool that can connect to MCP servers.

• To connect to a locally running server (compiled):

  mcp-inspector --stdio "node /path/to/your/mcp-promptregistry/dist/server.js"
  

• To connect to the Docker container:

  mcp-inspector --stdio "docker run -i --rm mcp-promptregistry" 
  

  (Replace mcp-promptregistry with your image name if different. Ensure mcp-inspector is installed and in your PATH.)

  The Inspector allows you to see available prompts and tools, make requests, and view responses interactively.

🧰 Using with Claude Desktop (Example Workflow)

Once MCP Prompt Registry is added as an MCP server in Claude Desktop (using one of the configurations above):

1. Discover Prompts: Your custom prompts should appear in Claude Desktop's prompt library or be accessible via its command interface (e.g., by typing / or similar, depending on Claude's UI). The description you set in your prompt's JSON file will be visible.
2. Select a Prompt: Choose one of your prompts.
3. Fill Arguments: If the prompt has variables (e.g., {{concept}}, {{age}}), Claude Desktop should provide UI fields for you to enter these values. The description for each variable (from your prompt's JSON) can guide the user.
4. Execute: Claude Desktop will send a prompts/get request to your server with the filled arguments. Your server will apply the template and return the final prompt content to Claude.
5. Management Tools: To use tools like add_prompt or filter_prompts_by_tags from Claude Desktop, Claude would need a way to send arbitrary tools/call requests to connected MCP servers. If this isn't directly supported, you'd typically use MCP Inspector or manual stdio alongside Claude for management tasks.

🛠️ Available Management Tools

Your MCP Prompt Registry exposes the following tools (callable via MCP tools/call requests):

• add_prompt: Adds a new prompt to the prompt directory.
  • Args: id, content, description (optional), tags (optional), variables (optional), metadata (optional).
• get_prompt_file_content: Retrieves the raw JSON definition of the prompt.
  • Args: id.
• update_prompt: Updates an existing prompt.
  • Args: id, and any fields to update (content, description, etc.).
• delete_prompt: Deletes a prompt from the prompt directory.
  • Args: id.
• filter_prompts_by_tags: Lists prompts that match all specified tags. Returns a summary (id, description, tags).
  • Args: tags (array of strings).
• load_default_prompts: Copies all prompts from the default_prompts_data/ directory (if present) into the active prompt directory, skipping any that already exist. Useful for populating or restoring default prompts.
  • Args: None.

example

⚠️ Troubleshooting & Gotchas

• Stdio Server Logging: Remember, console.log() in your server.ts will break MCP communication over stdio because it writes to stdout. All server-side diagnostic/status logs should use console.error(), which writes to stderr. For logs you want the client to potentially see, use MCP's logging capability via context.sendNotification in tool handlers (if the client supports it).
• Server Startup Messages on Stderr: Some initial server startup messages, such as directory creation or automatic default prompt loading, will appear on stderr (e.g., Attempting to create prompt directory: /Users/stevengonsalvez/.promptregistry or Auto-loaded 2 default prompt(s) into ~/.promptregistry: code-review-assistant, prompt-writing-assistant). This is because stdout is reserved for MCP JSON-RPC messages, and these startup actions occur before a client context is available for sendNotification.
• Permissions: Ensure the server process has write permissions for the prompt directory.
• JSON Validity: Ensure your prompt JSON files are valid.
• Absolute Paths for Clients: When configuring clients with local server paths, always use absolute paths.

🌱 Contributing & Future Ideas

This is a starting point! Future enhancements could include:

• More sophisticated templating.
• A watch mode to auto-reload prompts when files change.
• Support for other storage backends (e.g. postgres, github (or gists), sqllite).

Pull requests and ideas are welcome!