Prompt Optimizer
An MCP server and web tool for improving prompts: three tools for optimizing system and user prompts with iterative refinement
Medium risk
We rate an entry medium when the tool runs code, makes network calls or reads project files. Check what exactly it does before installing.
Why this level
- It sends prompt text to the configured LLM provider for optimization
Install
Manual install
docker run -d -p 8081:80 -e VITE_OPENAI_API_KEY=your-openai-key -e MCP_DEFAULT_MODEL_PROVIDER=openai --name prompt-optimizer linshen/prompt-optimizerStarts the web UI and the MCP server together; MCP is available at /mcp.
This is third-party code. Review the repository files before installing.
What it does
Prompt Optimizer takes a draft prompt and rewrites it so the model gives a more precise, predictable answer. Through MCP it exposes three tools: optimizing a user prompt, optimizing a system prompt, and iteratively refining an already-solid prompt against a specific requirement. Besides the MCP server, the project has a web app, a desktop app and a Chrome extension with the same optimization logic, testing, result evaluation and a library of saved prompts.
Who it is for. For anyone who writes LLM prompts regularly and wants better, more stable wording without manually trying variants.
Good fit when
- You need to improve a system or user prompt right from an agent conversation
- The prompt already works but needs targeted refinement for a new requirement
- You need a prompt library with version history and tests
Not a fit when
- The prompt is one-off and simple, so going through MCP is overkill
- No LLM provider API key is configured for the optimizer itself
Example request
Optimize this system prompt via prompt-optimizer so the model stays on topic more reliablyLimitations
The optimizer itself calls a separate LLM, so at least one provider API key is required (OpenAI, Gemini, DeepSeek, Zhipu and others, including local ones via Ollama). The MCP server is not published as a standalone npm package; it is installed via the Docker image or built from the monorepo source. Licensed under AGPL-3.0.
How to disable. Stop and remove the container: docker stop prompt-optimizer && docker rm prompt-optimizer, and remove the MCP server from the agent config.
MCP
- Transport
- http
- Authentication
- not required
| Environment variables | |
|---|---|
| VITE_OPENAI_API_KEY secret | One of the supported LLM provider keys; at least one is required. |
| MCP_DEFAULT_MODEL_PROVIDER required | The default provider used for optimization requests. |
Security check
- It sends prompt text to the configured LLM provider for optimization
README in short
The README describes Prompt Optimizer as a prompt-optimization tool with four usage paths: web app, desktop, Chrome extension and Docker deployment. A separate MCP server document lists three tools: optimize-user-prompt, optimize-system-prompt and iterate-prompt, running over Streamable HTTP, and shows connecting to Claude Desktop via a services.json file.
FAQ
Is Docker mandatory?
No, the README also describes a local pnpm build for developers, but Docker is the recommended path for regular users.
Which provider does the optimizer itself need?
At least one supported key: OpenAI, Gemini, DeepSeek, Grok, SiliconFlow, Zhipu, or a custom endpoint such as Ollama.
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