PromptForge MCP Server

An MCP tool that reengineer prompts using expert prompt engineering methodology via promptforge.ai.amazon.dev.

Prerequisites

• Node.js 20+ — download
• Midway authentication — run mwinit (standard on all Amazon corp machines)

Install (one line)

No install required. Add this to your MCP client config and it auto-downloads on first run:

Kiro / Kiro CLI

Add to ~/.kiro/settings/mcp.json:

{
  "mcpServers": {
    "promptforge": {
      "command": "npx",
      "args": ["--registry", "https://registry.npmjs.org", "-y", "promptforge-ai-mcp"]
    }
  }
}

Amazon Q Developer

Add to ~/.aws/amazonq/mcp.json:

{
  "mcpServers": {
    "promptforge": {
      "command": "npx",
      "args": ["--registry", "https://registry.npmjs.org", "-y", "promptforge-ai-mcp"]
    }
  }
}

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "promptforge": {
      "command": "npx",
      "args": ["--registry", "https://registry.npmjs.org", "-y", "promptforge-ai-mcp"]
    }
  }
}

Alternative: global install

npm install -g promptforge-ai-mcp --registry https://registry.npmjs.org

Then reference as:

{ "command": "promptforge-ai-mcp" }

Tool: optimize_prompt

Input:

• prompt (string, required) — The prompt to optimize
• mode (string, optional, default: "general") — Optimization mode:
  • general — Balanced optimization across structure, clarity, and efficiency
  • concise — Token reduction, remove fluff without losing quality
  • detailed — Expand with examples, edge cases, and constraints
  • code_generation — Optimize for code output quality
  • agentic — Optimize for agent/tool-use (ReAct patterns, guardrails)
  • system_prompt — Four-layer system prompt architecture

Output:

• Optimized prompt (ready to copy/paste)
• Changes summary (what was improved and why)
• Analysis (diagnosis of the original prompt)
• Token usage

How It Works

Your Agent → MCP Server (local) → promptforge.ai.amazon.dev/api/optimize → Claude Sonnet 4
                                        ↑
                              Midway cookie auth (~/.midway/cookie)

The MCP server reads your Midway cookies (written by mwinit) and authenticates with the PromptForge API. No AWS credentials, no API keys — just mwinit.

Troubleshooting

| Error | Fix | |-------|-----| | FETCH_ERROR / invalid json response body from npmpm.corp.amazon.com | Your npm is configured to use the internal Amazon registry. This package is on public npm. See fix below. | | Midway cookie file not found | Run mwinit in your terminal | | Midway session expired | Run mwinit to refresh | | 403 Forbidden | Run mwinit, ensure you have PromptForge bindle access | | 429 Rate limit | Wait a moment and retry |

Corporate npm registry conflict

If npx fails with a redirect to midway-auth.amazon.com, your .npmrc points to the internal Amazon registry (npmpm.corp.amazon.com). Since this package is published on public npm, add --registry to bypass it:

npx --registry https://registry.npmjs.org -y promptforge-ai-mcp --setup

Or for the MCP config (permanent fix — add the registry flag to args):

{
  "mcpServers": {
    "promptforge": {
      "command": "npx",
      "args": ["--registry", "https://registry.npmjs.org", "-y", "promptforge-ai-mcp"]
    }
  }
}

Alternatively, install globally once and reference the binary directly:

npm install -g promptforge-ai-mcp --registry https://registry.npmjs.org

Cross-Platform

Works identically on macOS and Windows:

• Pure JavaScript — no native compilation or OS-specific binaries
• mwinit writes ~/.midway/cookie on both platforms
• Node.js os.homedir() resolves the correct path on each OS

Development

cd mcp
npm install
npm run build
node dist/index.js  # runs the server locally via stdio