mcp-second-opinion

An MCP server that gets you a second opinion. It asks the same question to a panel of LLMs from different providers — in parallel, through a single OpenRouter key — and hands back every answer side by side. Optionally it synthesizes them, and is told to surface where the models disagree instead of averaging it into a confident-sounding blur.

One model can be confidently wrong. A panel that's forced to disagree is much harder to fool — so give your agent (Claude Desktop, or any MCP client) the ability to check a claim against three minds before trusting one.

You → second_opinion("Is this SQL injection-safe?", synthesize: true)

  ## openai/gpt-4o-mini      → "Yes, parameterised — safe."
  ## anthropic/claude-3.5-haiku → "No — the ORDER BY clause is interpolated."
  ## google/gemini-2.5-flash → "Safe for the WHERE clause; ORDER BY is a risk."

  ## 🔎 Synthesis
  Disagreement: the ORDER BY interpolation. Two of three flag it. Bottom line: not safe.

Why

• Cross-provider by design. OpenRouter proxies OpenAI / Anthropic / Google / Meta / … behind one OpenAI-compatible endpoint, so a real multi-provider panel needs only one API key.

• Resilient by construction. Members run with Promise.allSettled and a per-model timeout. A slow or failing model is reported as one failed answer — it never sinks the batch. (Covered by tests.)

• Disagreement is the point. The synthesizer is explicitly instructed to name conflicts, not smooth them away.

Related MCP server: Multi-Model Advisor

Install

Requires Node ≥ 18 and an OpenRouter API key (free to create at https://openrouter.ai/keys).

git clone https://github.com/aleksbuss/mcp-second-opinion.git
cd mcp-second-opinion
npm install
npm run build

Add it to Claude Desktop

Edit claude_desktop_config.json (Claude → Settings → Developer → Edit Config):

{
  "mcpServers": {
    "second-opinion": {
      "command": "node",
      "args": ["/absolute/path/to/mcp-second-opinion/dist/index.js"],
      "env": {
        "OPENROUTER_API_KEY": "sk-or-..."
      }
    }
  }
}

Restart Claude Desktop; the second_opinion and list_panel_models tools appear.

Tools

second_opinion

list_panel_models

Returns the configured default panel and how to override it. No arguments.

Configuration (environment)

Any model id on https://openrouter.ai/models works. Pick a cheap, fast panel — you're paying for N calls per question.

Develop

npm run typecheck   # tsc --noEmit
npm test            # vitest (mocks fetch; no network, no key needed)
npm run build       # → dist/
npm run dev         # run from source via tsx

The core fan-out and synthesis logic lives in src/panel.ts and is pure + fetch-injectable, so the resilience behaviour (one member failing, timeouts) is unit-tested without touching the network.

License

MIT © Aleksejs Buss