Which integrations are available for this server?

Provides direct API integration for prompt refinement using Google's Gemini models (2.0 Flash, 1.5 Pro), enabling LLM-powered prompt optimization and analysis. Provides direct API integration for prompt refinement using OpenAI models (GPT-4o, GPT-4o-mini, GPT-4 Turbo), enabling LLM-powered prompt optimization and analysis. Provides session store support for distributed multi-instance deployments and caching of refined prompts to improve performance.

How do I use PromptTuner MCP?

1. Click on "Install Server". 2. Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state. 3. In the chat, type @ followed by the MCP server name and your instructions, e.g., "@PromptTuner MCP refine this prompt to make it clearer and more effective" That's it! The server will respond to your query, and you can continue using it as needed. Here is a step-by-step guide with screenshots.

PromptTuner MCP

npm version License Node.js Version

PromptTuner MCP is an MCP server that fixes and boosts prompts using OpenAI, Anthropic, or Google Gemini.

What it does

Validates and trims input prompts (enforces MAX_PROMPT_LENGTH).
Wraps the prompt as JSON inside sentinel markers (sanitizing markers, bidi control chars, and null bytes).
Calls the selected provider.
Normalizes LLM output (strips code fences / labels if present).
Returns human-readable text plus machine-friendly structuredContent.

Features

Polish and refine a prompt for clarity and flow (fix_prompt).
Boost and enhance a prompt for clarity and effectiveness (boost_prompt).
Craft a reusable workflow prompt for complex tasks (crafting_prompt).
Simple structured outputs.
Retry logic with exponential backoff for transient provider failures.

Quick Start

PromptTuner runs over stdio only. The dev:http and start:http scripts are compatibility aliases (no HTTP transport yet).

Claude Desktop

Add to claude_desktop_config.json:

{ "mcpServers": { "prompttuner": { "command": "npx", "args": ["-y", "@j0hanz/prompt-tuner-mcp-server@latest"], "env": { "LLM_PROVIDER": "openai", "OPENAI_API_KEY": "sk-..." } } } }

Replace the API key and provider with your preferred LLM. Only configure the key for the active provider.

Configuration

PromptTuner uses minimal configuration. Set the provider and API key, and you're ready to go.

Variable	Default	Description
`LLM_PROVIDER`	`openai`	`openai`, `anthropic`, or `google`.
`OPENAI_API_KEY`	-	Required for all tools when `LLM_PROVIDER=openai`.
`ANTHROPIC_API_KEY`	-	Required for all tools when `LLM_PROVIDER=anthropic`.
`GOOGLE_API_KEY`	-	Required for all tools when `LLM_PROVIDER=google`.
`LLM_MODEL`	-	Override the default model.
`DEBUG`	`false`	Enable debug logging.

All tools are LLM-backed and require an API key for the selected provider.

Default Models

Provider	Default Model
`openai`	`gpt-4o`
`anthropic`	`claude-3-5-sonnet-20241022`
`google`	`gemini-2.0-flash-exp`

CLI Options

Flag	Description
`-h, --help`	Show help text.
`-v, --version`	Print version.
`--debug / --no-debug`	Enable/disable debug logging.
`--llm-provider <provider>`	`openai`, `anthropic`, or `google`.
`--llm-model <name>`	Override the default model.

Tools

All tools accept plain text, Markdown, or XML prompts. Responses include content (human-readable) and structuredContent (machine-readable). Inputs are strict: extra fields are rejected. For fix_prompt/boost_prompt, only the prompt field is accepted.

fix_prompt

Polish and refine a prompt for clarity and flow while preserving intent and structure.

Parameter	Type	Required	Notes
`prompt`	string	Yes	Trimmed, length-checked; extra fields rejected.

Returns: ok, fixed.

boost_prompt

Refine and enhance a prompt for clarity and effectiveness.

Parameter	Type	Required	Notes
`prompt`	string	Yes	Trimmed, length-checked; extra fields rejected.

Returns: ok, boosted.

crafting_prompt

Generate a structured, reusable workflow prompt for complex tasks based on a raw request and a few settings.

Parameter	Type	Required	Notes
`request`	string	Yes	Trimmed, length-checked; strict input.
`constraints`	string	No	Hard requirements to enforce (bullet list recommended).
`mode`	string	No	`general`, `plan`, `review`, `troubleshoot`.
`approach`	string	No	`conservative`, `balanced`, `creative`.
`tone`	string	No	`direct`, `neutral`, `friendly`.
`verbosity`	string	No	`brief`, `normal`, `detailed`.

Returns: ok, prompt, settings.

Response Format

content: array of content blocks. First block is JSON for structuredContent, second is a short human message (or Error: ...).
structuredContent: machine-parseable results.
Errors return structuredContent.ok=false and an error object with code, message, optional context (sanitized, up to 200 chars), details, and recoveryHint.
Error responses also include isError: true.

Development

Prerequisites

Node.js >= 22.0.0
npm

Scripts

Command	Description
`npm run build`	Compile TypeScript and set permissions.
`npm run prepare`	Build on install (publishing helper).
`npm run dev`	Run from source in watch mode.
`npm run dev:http`	Alias of `npm run dev` (no HTTP transport yet).
`npm run watch`	TypeScript compiler in watch mode.
`npm run start`	Run the compiled server from `dist/`.
`npm run start:http`	Alias of `npm run start` (no HTTP transport yet).
`npm run test`	Run `node:test` once.
`npm run test:coverage`	Run `node:test` with experimental coverage.
`npm run test:watch`	Run `node:test` in watch mode.
`npm run lint`	Run ESLint.
`npm run format`	Run Prettier.
`npm run type-check`	TypeScript type checking.
`npm run inspector`	Run MCP Inspector against `dist/index.js`.
`npm run inspector:http`	Alias of `npm run inspector` (no HTTP transport yet).
`npm run duplication`	Run jscpd duplication report.
`npm run prepublishOnly`	Lint, type-check, and build before publish.

Project Structure

src/ index.ts Entry point cli.ts CLI parsing, logging bootstrap, shutdown handling server.ts MCP server setup (stdio transport) tools.ts Tool implementations schemas.ts Zod input/output schemas config.ts Configuration and constants types.ts Shared types and error codes lib/ Shared utilities (LLM, retry, telemetry, prompt utils) tests/ node:test suites dist/ Compiled output (generated) docs/ Static assets

Security

API keys are supplied only via environment variables.
Inputs are validated with Zod and additional length checks.
Error context is included in debug mode (sanitized and truncated to 200 chars).
Google safety filters are always enabled.

Contributing

Pull requests are welcome. Please include a short summary, tests run, and note any configuration changes.

License

MIT License. See LICENSE for details.

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A

security – no known vulnerabilities

F

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A

quality - confirmed to work

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PromptTuner MCP

PromptTuner MCP

What it does

Features

Quick Start

Claude Desktop

Configuration

Default Models

CLI Options

Tools

fix_prompt

boost_prompt

crafting_prompt

Response Format

Development

Prerequisites

Scripts

Project Structure

Security

Contributing

License

Resources

Tools

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