Ensemble Mcp

ensemble-mcp

A paid MCP server that sells one capability to AI agents: a multi-model ensemble. Agents pay per request in USDC via x402 on Base.

What the paid tool does

ensemble_query(question) runs a 3-round pipeline where models learn from each other:

Round	What happens	Report file
1 — Draft	Each model (Claude, GPT, Gemini) answers independently	reports/<job>/<model>.round1.md
2 — Cross-review	Each model reads the other models' drafts, critiques, and revises its own	reports/<job>/<model>.round2.md
3 — Master	A master model merges the revised reports into one attributed answer	reports/<job>/master.md

Every model gets its own report file per round, and the whole exchange happens over the Model Context Protocol on the outside — pay once, get the synthesized result.

Deploy in one click

Option A — Render.com (easiest)

1. Push this repo to GitHub.
2. Click →
3. Fill in PAY_TO_ADDRESS and at least one model API key in the Render dashboard.
4. Done — Render auto-deploys on every push to main.

Option B — Fly.io (~$5/mo, zero idle cost)

brew install flyctl && fly auth login
fly launch --no-deploy          # creates app, detects fly.toml
fly secrets set \
  PAY_TO_ADDRESS=0xYOUR_WALLET \
  ANTHROPIC_API_KEY=sk-ant-... \
  OPENAI_API_KEY=sk-...         # optional
fly deploy                      # builds + deploys in ~90 s

Option C — local dev

cp .env.example .env   # fill in PAY_TO_ADDRESS + at least one model API key
npm install
npm run dev

• GET / and GET /health are free (service discovery).
• POST /mcp returns HTTP 402 Payment Required with a price quote until the client retries with a valid X-PAYMENT header. The facilitator verifies and settles the USDC transfer, then the request goes through.

Testing the payment flow (testnet, free)

1. Keep X402_NETWORK=base-sepolia and the default facilitator.
2. Get free testnet USDC from the Circle faucet (Base Sepolia).
3. Use an x402-capable client — e.g. x402-fetch or x402-axios from the x402 repo — pointed at http://localhost:3000/mcp, or wire it into an MCP client config.

Going live (real revenue)

1. Set X402_NETWORK=base and switch FACILITATOR_URL to Coinbase CDP's mainnet facilitator (see docs.cdp.coinbase.com/x402).
2. Deploy anywhere Node runs — Render, Fly.io, Railway, a VPS. (Vercel/Cloudflare also support x402 natively; this codebase is plain Express so a small adapter is needed for Workers.)
3. List the server in x402/MCP discovery indexes (e.g. the x402 Bazaar) so agents can find it.

USDC lands directly in PAY_TO_ADDRESS — no invoicing, no Stripe, no API-key billing.

Pricing math

At $0.05/call, your cost is the underlying model tokens (~$0.01–0.03 per ensemble run at 2k-token caps). Tune PRICE_USD, max_tokens, and the model list for margin.

Extending

• Add members: edit getEnsembleMembers() in src/providers.ts.
• Add more paid tools: register them in buildMcpServer() in src/index.ts and add routes to the paymentMiddleware config (different prices per tool/route are supported).
• Persist reports to S3/R2 instead of local disk: swap saveReport() in src/ensemble.ts.