FlowyPrompt MCP Server

Version: 2.0.0 (MCP Transformation Complete) Status: Production Ready - Full MCP Protocol Support

Model Context Protocol (MCP) server for Claude Desktop integration, providing prompt template management with automatic variable extraction, substitution, and GitHub repository synchronization.

🌐 Web App: flowyprompt.com - Create and manage prompt templates online

🎯 Features

• 🤖 Claude Desktop Integration: Native MCP protocol support via stdio transport

• 📝 Automatic Variable Extraction: Detects {variable} placeholders in templates (FlowyPrompt format)

• 🔄 Smart Caching: 15-minute TTL with ETag revalidation from GitHub

• ⚡ High Performance: <100ms prompt generation, <300ms cached fetches

• 🔐 Secure: GitHub PAT authentication, input validation, no exposed ports

• 📊 Observable: Built-in metrics and health check tools

• ✅ Test-Driven: Comprehensive test coverage with TDD methodology

Related MCP server: mcp-prompt-engine

🚀 Quick Start

Prerequisites

• Node.js ≥18.0.0

• npm or yarn

• GitHub Personal Access Token (PAT) with repository read access

• Claude Desktop app

GitHub PAT Token Permissions

When creating your GitHub Personal Access Token, ensure it has the following permissions:

Required Scopes:

• repo - Full control of private repositories

  • repo:status - Access commit status

  • repo_deployment - Access deployment status

  • public_repo - Access public repositories

  • repo:invite - Access repository invitations

  • security_events - Read and write security events

Alternative (Minimal) Scopes: If you only need to access public repositories, you can use:

• public_repo - Access public repositories only

Token Creation Steps:

1. Go to GitHub → Settings → Developer settings → Personal access tokens → Tokens (classic)

2. Click "Generate new token (classic)"

3. Select the repo scope (or public_repo for public repos only)

4. Copy the generated token (starts with ghp_)

5. Use this token as the GITHUB_PAT value in your Claude Desktop configuration

Installation

# Clone repository
git clone https://github.com/your-org/flowyprompt_mcp.git
cd flowyprompt_mcp

# Install dependencies
npm install

# That's it! No .env file needed (and should NOT be created).
# All configuration MUST be done in Claude Desktop's config file.
# Creating .env will break MCP protocol (stdout pollution).

Claude Desktop Configuration

No .env file needed! All configuration is done through Claude Desktop's config file.

Add the MCP server to your Claude Desktop configuration file:

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

{
  "mcpServers": {
    "flowyprompt": {
      "command": "node",
      "args": ["/absolute/path/to/flowyprompt_mcp/index.js"],
      "env": {
        "GITHUB_PAT": "ghp_your_github_personal_access_token",
        "GITHUB_REPO_URL": "https://github.com/your-org/your-templates-repo",
        "GITHUB_REF": "main",
        "MCP_SERVER_NAME": "flowyprompt-mcp-server",
        "MCP_SERVER_VERSION": "1.0.0",
        "CACHE_TTL_MS": "900000",
        "MAX_FILE_SIZE": "102400",
        "LOG_LEVEL": "info"
      }
    }
  }
}

Configuration Notes:

• ✅ All environment variables are set in claude_desktop_config.json

• ✅ No .env file needed in the project directory

• ⚠️ Use absolute paths for args (e.g., /Users/name/flowyprompt_mcp/index.js)

• ⚠️ GITHUB_PAT and GITHUB_REPO_URL are required

• 💡 Example config file: See mcp_config.example.json in the repository

Claude Code Configuration (VS Code)

Use the same configuration format as Claude Desktop. If Claude Code supports file references, you can include the same file directly using:

"@mcp_config.example.json"

JSON-based MCP Clients (e.g., Gemini)

Use the same configuration. If your client supports @file includes, reference the shared example config:

"@mcp_config.example.json"

"@file" include format

Some clients support referencing an external JSON file by using a string that begins with @. You can reuse an existing config with:

"@mcp_config.example.json"

This keeps a single source of truth across clients.

Verify Installation

1. Restart Claude Desktop after updating the config

2. Check MCP connection: Look for the 🔌 icon in Claude Desktop

3. List prompts: Click "+" button to see available templates

4. Use health check: Run the health_check tool to verify configuration

📡 MCP Features

Note: HTTP Streamable MCP is not yet supported. This server currently only supports stdio transport for Claude Desktop integration.

➕ Prompts (Quick Template Access)

Use the "+" button in Claude Desktop to access prompt templates with variable set support.

How to use:

1. Click the "+" button in Claude Desktop

2. Select a template from the list

3. Choose a pre-filled variable set by entering "X" in the _useSet_XXX field

4. Or manually enter individual variable values

Variable Sets:

• Templates can include pre-defined variable sets

• Each set shows a preview: target=q, audience=w, requirements=d

• Enter "X" in the _useSet_var1 field to use that variable set

• All variables are automatically filled

Benefits:

• ✅ Quick access to templates via UI

• ✅ Pre-filled variable sets for common use cases

• ✅ Visual argument list with descriptions

🔨 MCP Tools

prompts/list

List all available prompt templates from your GitHub repository.

Parameters: None (optional ref for git branch/tag)

Example:

Tool: prompts/list

Returns:

{
  "prompts": [
    {
      "name": "Brand_Positioning_Strategy",
      "description": "Develop comprehensive brand positioning strategy",
      "arguments": [
        {"name": "company_name", "description": "Your company name", "required": true},
        {"name": "industry", "description": "Your industry", "required": true}
      ]
    }
  ]
}

prompts/get

Get a specific prompt template with automatic variable substitution.

Parameters:

• name (required): Template name (without .json extension)

• variables (optional): Object with variable values for substitution

• ref (optional): Git reference (branch/tag/commit)

Example:

Tool: prompts/get
{
  "name": "Brand_Positioning_Strategy",
  "variables": {
    "company_name": "Acme Corp",
    "industry": "Technology"
  }
}

Returns:

{
  "description": "Develop Solution Template",
  "content": "develop a template for Acme Corp targeting Technology with Strict requirements.",
  "arguments": [
    {"name": "_variableSet", "description": "Select a pre-filled variable set", "required": false},
    {"name": "_useSet_var1", "description": "Use \"var1\" (enter X to use): target=q, audience=w, requirements=d", "required": false},
    {"name": "target", "description": "Value for target", "required": false},
    {"name": "audience", "description": "Value for audience", "required": false},
    {"name": "requirements", "description": "Value for requirements", "required": false}
  ],
  "isError": false
}

health_check

Check MCP server health and configuration status.

Parameters: None

Example:

Tool: health_check

Returns:

{
  "status": "healthy",
  "server": {
    "name": "flowyprompt-mcp-server",
    "version": "1.0.0"
  },
  "config": {
    "githubRepo": "https://github.com/owner/repo",
    "githubRef": "main",
    "cacheType": "memory",
    "cacheTtlMs": 900000
  },
  "uptime": 3600,
  "timestamp": "2025-01-06T10:30:00.000Z"
}

get_metrics

Get server performance and usage metrics.

Parameters: None

Example:

Tool: get_metrics

Returns:

{
  "requests": {
    "total": 42,
    "success": 40,
    "errors": 2,
    "byType": {"template": 42, "flow": 0}
  },
  "cache": {
    "hits": 30,
    "misses": 12,
    "hitRate": 71
  },
  "latency": {
    "min": 45,
    "max": 1850,
    "avg": 180,
    "p50": 120,
    "p95": 850,
    "p99": 1600
  },
  "mcp": {
    "promptGeneration": {
      "count": 40,
      "latencyMs": {"min": 12, "max": 95, "avg": 35}
    },
    "tools": {
      "prompts_list": {"count": 5, "errors": 0},
      "prompts_get": {"count": 40, "errors": 2}
    }
  }
}

get_variable_sets

Get pre-filled variable value sets for a template.

Parameters:

• name (required): Template name (without .json extension)

• setName (optional): Specific variable set name to get filled template

• ref (optional): Git reference (branch/tag/commit)

Example 1 - List all variable sets:

Tool: get_variable_sets
{
  "name": "Develop_Solution_Template"
}

Returns:

{
  "template": "Develop_Solution_Template",
  "sets": [
    {
      "id": "77eae1c3-67ef-4124-8eb1-02e129709a07",
      "name": "var1",
      "description": "",
      "variables": {
        "target": "q",
        "audience": "w",
        "requirements": "d"
      },
      "variableCount": 3
    }
  ],
  "totalSets": 1
}

Example 2 - Get specific variable set with filled template:

Tool: get_variable_sets
{
  "name": "Develop_Solution_Template",
  "setName": "var1"
}

Returns:

{
  "template": "Develop_Solution_Template",
  "setName": "var1",
  "description": "",
  "variables": {
    "target": "q",
    "audience": "w",
    "requirements": "d"
  },
  "filledTemplate": "develop a template for q targeting w with d."
}

🔗 Flow Execution

Execute multi-step template chains where the output of one template automatically flows into the input variables of subsequent templates.

flows/list

List all available flow templates from your GitHub repository.

Parameters:

• includeMetadata (optional): Include created/updated timestamps. Default: true

• ref (optional): Git reference (branch/tag/commit)

Example:

Tool: flows/list

Returns:

{
  "flows": [
    {
      "name": "Marketing_Strategy",
      "description": "Generate comprehensive marketing strategy with market analysis and content plan",
      "version": "1.0.0",
      "nodeCount": 3,
      "created": "2025-01-06T10:00:00.000Z",
      "updated": "2025-01-06T10:00:00.000Z"
    }
  ],
  "cached": false
}

flows/execute

Execute a multi-step flow where template outputs feed into subsequent template inputs.

Parameters:

• flowName (required): Flow name (without .json extension)

• initialVariables (required): Initial variable values for the flow

• ref (optional): Git reference (branch/tag/commit)

Example:

Tool: flows/execute
{
  "flowName": "Simple_Chain",
  "initialVariables": {
    "topic": "Artificial Intelligence in Healthcare"
  }
}

Returns:

{
  "flowName": "Simple_Chain",
  "executionId": "Simple_Chain_1704539400000",
  "intermediateResults": [
    {
      "nodeId": "node-1",
      "templateName": "Topic_Analysis",
      "inputVariables": {
        "topic": "Artificial Intelligence in Healthcare"
      },
      "output": "AI in healthcare analysis...",
      "executionTimeMs": 450,
      "timestamp": "2025-01-06T10:30:00.000Z"
    },
    {
      "nodeId": "node-2",
      "templateName": "Content_Summarizer",
      "inputVariables": {
        "topic": "Artificial Intelligence in Healthcare",
        "node1_result": "AI in healthcare analysis..."
      },
      "output": "Summary of AI in healthcare...",
      "executionTimeMs": 380,
      "timestamp": "2025-01-06T10:30:01.000Z"
    }
  ],
  "finalResult": "Summary of AI in healthcare...",
  "totalExecutionTimeMs": 830,
  "status": "success"
}

Variable Mapping:

• Previous node outputs are automatically available as {nodeX_result} variables

• Example: node-1's output becomes {node1_result} for subsequent nodes

• Initial variables remain available throughout the flow

Error Handling:

• If a template execution fails, partial results are returned

• The failedAt field indicates which node failed

• Example error response:

{
  "code": "TEMPLATE_NOT_FOUND",
  "message": "Template not found: InvalidTemplate",
  "partialResults": [
    {
      "nodeId": "node-1",
      "templateName": "Topic_Analysis",
      "output": "AI in healthcare analysis...",
      "executionTimeMs": 450
    }
  ],
  "failedAt": {
    "nodeId": "node-2",
    "templateName": "InvalidTemplate",
    "error": "Template not found"
  }
}

Flow Definition Example:

Flows are JSON files stored under flows/ in your GitHub repository, named as flows/<Flow_Name>.json.

{
  "metadata": {
    "name": "Simple_Chain",
    "description": "Two-step content analysis flow",
    "version": "1.0.0"
  },
  "nodes": [
    {
      "id": "node-1",
      "type": "template",
      "data": {
        "label": "Topic Analysis",
        "selectedTemplateId": "Topic_Analysis",
        "variables": ["topic"]
      }
    },
    {
      "id": "node-2",
      "type": "template",
      "data": {
        "label": "Summarizer",
        "selectedTemplateId": "Content_Summarizer",
        "variables": ["topic", "node1_result"]
      }
    }
  ],
  "edges": [
    {
      "id": "e1",
      "source": "node-1",
      "target": "node-2",
      "type": "chain"
    }
  ]
}

Key Features:

• ✅ Topological sort ensures correct execution order

• ✅ Circular dependency detection prevents infinite loops

• ✅ Partial results returned on failure for debugging

• ✅ Performance target: <5s for 3-node chains

🏗️ Template Format

Templates are JSON files stored under templates/ in your GitHub repository, named as templates/<Template_Name>.json.

This server supports the FlowyPrompt export structure. At minimum, place a top-level object with a templates array and store your prompt in the first element using {variable} placeholders and optional variableValueSets.

Example Template: templates/Develop_Solution_Template.json

{
  "metadata": {
    "version": "2.0",
    "exportDate": "2025-10-06T06:21:00.659Z",
    "templateCount": 1,
    "includeImages": false,
    "imageCount": 0,
    "fileName": "Develop_Solution_Template.json",
    "source": "FlowyPrompt Web App"
  },
  "templates": [
    {
      "id": "1758694568593",
      "title": "Develop Solution Template",
      "template": "develop a template for {target} targeting {audience} with {requirements}.",
      "variables": ["target", "audience", "requirements"],
      "createdAt": "2025-09-24T06:16:08.593Z",
      "updatedAt": "2025-10-06T06:20:26.966Z",
      "version": 2,
      "variableValueSets": [
        {
          "id": "77eae1c3-67ef-4124-8eb1-02e129709a07",
          "name": "var1",
          "description": "",
          "values": {"target": "q", "audience": "w", "requirements": "d"},
          "images": [],
          "result": "",
          "createdAt": "2025-10-06T06:20:26.962Z",
          "updatedAt": "2025-10-06T06:20:26.962Z"
        }
      ]
    }
  ]
}

Variable Syntax: Use {variable} placeholders Variable Sets: Select via _variableSet or _useSet_<name> in tool inputs Caching: Templates are cached with ETag-based revalidation

🏗️ Architecture

System Architecture

┌─────────────────┐
│  Claude Desktop │
└────────┬────────┘
         │ stdio
         ↓
┌─────────────────────────────────────┐
│     FlowyPrompt MCP Server          │
│  ┌──────────────────────────────┐   │
│  │   MCP Protocol Layer         │   │
│  │  - prompts/list handler      │   │
│  │  - prompts/get handler       │   │
│  │  - health/metrics tools      │   │
│  └──────────────┬───────────────┘   │
│                 │                    │
│  ┌──────────────▼───────────────┐   │
│  │   Service Layer              │   │
│  │  - promptService             │   │
│  │  - githubService             │   │
│  │  - cacheService              │   │
│  │  - metricsService            │   │
│  └──────────────┬───────────────┘   │
│                 │                    │
│  ┌──────────────▼───────────────┐   │
│  │   Utilities                  │   │
│  │  - logger, error handler     │   │
│  │  - config, validation        │   │
│  └──────────────────────────────┘   │
└──────────────┬──────────────────────┘
               │ HTTPS
               ↓
        ┌─────────────┐
        │ GitHub API  │
        │  (templates)│
        └─────────────┘

Directory Structure

flowyprompt_mcp/
├── src/
│   ├── mcp/
│   │   ├── server.js              # MCP server initialization
│   │   ├── tools/
│   │   │   ├── promptsList.js     # prompts/list tool
│   │   │   └── promptsGet.js      # prompts/get tool
│   │   └── formatters/
│   │       └── promptFormatter.js # MCP message formatting
│   ├── services/
│   │   ├── promptService.js       # Variable extraction & substitution
│   │   ├── githubService.js       # GitHub API integration
│   │   ├── cacheService.js        # Template caching
│   │   ├── metricsService.js      # Performance metrics
│   │   └── validationService.js   # Schema validation
│   ├── utils/
│   │   ├── logger.js              # Structured logging
│   │   └── errorHandler.js        # Error management
│   └── config/
│       └── index.js               # Configuration loader
├── tests/
│   ├── unit/                      # Unit tests
│   ├── mcp/                       # MCP integration tests
│   └── contract/                  # Contract tests
├── specs/
│   └── 002-mcp-claude-desktop/    # Design documents
├── index.js                       # Entry point
├── package.json
└── .env.example

Technology Stack

⚙️ Configuration

Environment Variables

All environment variables are configured in claude_desktop_config.json under the env section. No .env file is needed.

Note: For local development/testing, you can optionally create a .env file, but it's not required for Claude Desktop usage.

Cache Configuration

The MCP server uses in-memory caching with ETag-based revalidation:

• TTL: 15 minutes (configurable via CACHE_TTL_MS)

• Strategy: Cache-aside with automatic revalidation

• Invalidation: ETag-based, sends If-None-Match header

• Performance: 304 responses return cached content instantly

🧪 Testing

Run Tests

# All tests
npm test

# With coverage
npm run test:coverage

# Specific test file
npm test tests/unit/promptService.test.js

# Watch mode
npm run test:watch

Test Coverage

• Unit Tests: promptService (100% coverage)

• Contract Tests: MCP protocol compliance

• Integration Tests: stdio transport, cache revalidation

• Performance Tests: Prompt generation <100ms

Target Coverage: ≥85% (per project constitution)

📊 Performance Targets

🔐 Security

• GitHub PAT Protection: PAT automatically sanitized in all logs

• Input Validation: All inputs validated against JSON schemas

• No Network Exposure: stdio-only, no HTTP ports opened

• Path Traversal Prevention: Template names validated with regex

• Error Sanitization: Sensitive details removed from error messages

🐛 Troubleshooting

MCP Server Not Appearing in Claude Desktop

1. Check config file path:

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

   • Windows: %APPDATA%\Claude\claude_desktop_config.json

2. Verify absolute paths: Use full paths, not relative (e.g., /Users/name/project/index.js)

3. Check logs:

   tail -f ~/.local/state/claude/logs/mcp*.log

4. Test manually:

   node index.js
   # Should start without errors

Templates Not Loading

1. Verify GitHub credentials:

   # Test GitHub access
   curl -H "Authorization: token $GITHUB_PAT" \
        https://api.github.com/repos/owner/repo/contents/templates

2. Check template format: Ensure JSON is valid and follows schema

3. Use health_check tool: Verify GitHub connectivity in Claude Desktop

Performance Issues

1. Check cache hit rate: Use get_metrics tool

2. Verify network latency: Test GitHub API response times

3. Review logs: Check for retry attempts or errors

📚 Related Documentation

• Implementation Plan: specs/002-mcp-claude-desktop/plan.md

• Task Breakdown: specs/002-mcp-claude-desktop/tasks.md

• Data Model: specs/002-mcp-claude-desktop/data-model.md

• API Contracts: specs/002-mcp-claude-desktop/contracts/

• Research Decisions: specs/002-mcp-claude-desktop/research.md

• Quickstart Guide: specs/002-mcp-claude-desktop/quickstart.md

• CHANGELOG: CHANGELOG.md

🤝 Contributing

This project follows Test-Driven Development principles:

1. Write failing tests first (RED)

2. Implement minimal code to pass (GREEN)

3. Refactor for quality (REFACTOR)

All contributions must:

• Include comprehensive tests

• Maintain ≥85% code coverage

• Follow ESLint and Prettier conventions

• Include JSDoc comments

• Update CHANGELOG.md

📜 Constitutional Compliance

This implementation adheres to the FlowyPrompt MCP Constitution v1.0.0:

• ✅ I. Modularity & Isolation: Layered architecture (MCP/Service/Utility)

• ✅ II. Schema-First Validation: AJV validation for all templates

• ✅ III. Test-Driven Development: Tests written before implementation

• ✅ IV. Security-First Design: PAT protection, input validation, no exposed ports

• ✅ V. Performance & Efficiency: Caching, async I/O, <100ms prompt generation

• ✅ VI. UX Consistency: Standardized MCP protocol, clear error messages

• ✅ VII. Code Quality: ESLint, Prettier, JSDoc, 100% test coverage for core services

📄 License

MIT License - FlowyPrompt Team

🙏 Acknowledgments

• Built with MCP SDK

• Designed for Claude Desktop

• Follows Test-Driven Development

Built with Claude Code using Test-Driven Development and constitutional governance principles.

Version 2.0.0 - Complete MCP transformation from HTTP REST API