MCP Rubber Duck MCP Server

An MCP server that bridges to multiple OpenAI-compatible LLMs - your AI rubber duck debugging panel

Local serverstdio

What is the MCP Rubber Duck MCP server?

If you already use MCP Rubber Duck, the mcp rubber duck mcp server is the piece that lets your assistant work with it directly. An MCP server that bridges to multiple OpenAI-compatible LLMs - your AI rubber duck debugging panel.

What the server does

An MCP (Model Context Protocol) server that acts as a bridge to query multiple LLMs -- both OpenAI-compatible HTTP APIs and CLI coding agents. Just like rubber duck debugging, explain your problems to various AI "ducks" and get different perspectives!

  • Universal OpenAI Compatibility — -- Works with any OpenAI-compatible API endpoint
  • CLI Agent Support — -- Use CLI coding agents (Claude Code, Codex, Gemini CLI, Grok, Aider) as ducks
  • Multiple Ducks — -- Configure and query multiple LLM providers simultaneously
  • Conversation Management — -- Maintain context across multiple messages
  • Duck Council — -- Get responses from all your configured LLMs at once
  • Consensus Voting — -- Multi-duck voting with reasoning and confidence scores

Available tools

The toolset is worth reading before you wire it up, because it tells you what the integration is really for:

  • OpenAIGoogle Gemini
  • ask_duck — Ask a single question to a specific LLM provider
  • chat_with_duck — Conversation with context maintained across messages
  • clear_conversations — Clear all conversation history
  • list_ducks — List configured providers and health status
  • list_models — List available models for providers
  • compare_ducks — Ask the same question to multiple providers simultaneously
  • duck_council — Get responses from all configured ducks
  • get_usage_stats — Usage statistics and estimated costs
  • duck_vote — Multi-duck voting with reasoning and confidence
  • duck_judge — Have one duck evaluate and rank others' responses
  • duck_iterate — Iteratively refine a response between two ducks

Credentials and setup notes

Configuration is passed through the environment: OPENAI_API_KEY, GEMINI_API_KEY, GROQ_API_KEY. Treat anything key-shaped as a real credential — scope it to the minimum the server needs, and rotate it if it ever lands in a shared config.

  • Node.js 20 or higher - npm or yarn - At least one API key for an HTTP provider, or a CLI coding agent installed locally

Installation

Installation goes through your MCP client rather than a global install: point it at directly on npm and it is fetched when the client starts. The copy-paste blocks for Claude Desktop, Claude Code and Cursor are further down this page.

Where it fits

Among the AI and media services options, the useful question is rarely "what can it do" but "what does it cost you to run" — permissions, credentials, and how much of your context its toolset consumes. MCP Rubber Duck's toolset — OpenAI, ask_duck, chat_with_duck and 11 more — is a fair guide to whether it matches your workflow. It is maintained by nesquikm; worth a glance at recent repository activity before you build anything load-bearing on it.

SyncDev reviews every entry in this directory against the project's own documentation before publishing, and revisits them as servers change.

Worth knowing first

  • It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
  • With 14 tools registered it takes up a noticeable share of the context window; turn it off in projects that never touch MCP Rubber Duck.
  • Missing credentials fail quietly in some clients — if no tools show up, check the environment block first.
  • Keep per-call confirmation enabled while you learn its behaviour; it is the cheapest safeguard you have.

Available tools

ToolWhat it does
OpenAI**Google Gemini**
ask_duckAsk a single question to a specific LLM provider
chat_with_duckConversation with context maintained across messages
clear_conversationsClear all conversation history
list_ducksList configured providers and health status
list_modelsList available models for providers
compare_ducksAsk the same question to multiple providers simultaneously
duck_councilGet responses from all configured ducks
get_usage_statsUsage statistics and estimated costs
duck_voteMulti-duck voting with reasoning and confidence
duck_judgeHave one duck evaluate and rank others' responses
duck_iterateIteratively refine a response between two ducks
duck_debateStructured multi-round debate between ducks
mcp_statusMCP Bridge status and connected servers

How to install the MCP Rubber Duck MCP server

{
  "mcpServers": {
    "rubber-duck": {
      "command": "npx",
      "args": ["-y", "directly"],
      "env": {
        "OPENAI_API_KEY": "your-value",
        "GEMINI_API_KEY": "your-value",
        "GROQ_API_KEY": "your-value"
      }
    }
  }
}

Add to claude_desktop_config.json, then restart Claude Desktop.

Configuration

  • Node.js 20 or higher - npm or yarn - At least one API key for an HTTP provider, or a CLI coding agent installed locally
VariableDescriptionRequired
OPENAI_API_KEYCredential the server authenticates with.Yes
GEMINI_API_KEYCredential the server authenticates with.Yes
GROQ_API_KEYCredential the server authenticates with.Yes

Example prompts to try

  • Use MCP Rubber Duck to OpenAI.
  • Use MCP Rubber Duck to ask duck.
  • Use MCP Rubber Duck to chat with duck.

Frequently asked questions

It connects MCP Rubber Duck to MCP-compatible AI assistants such as Claude and Cursor, exposing 14 tools (OpenAI, ask_duck, chat_with_duck, and more) that the assistant can call on your behalf. Instead of copying data back and forth by hand, the assistant works with MCP Rubber Duck directly.