DopamineDesk x402 Marketplace MCP Server

Decision-ready machine-to-machine reports paid per request with the x402 Payment Protocol on Base Mainnet.

No API key. No account. No subscription. Buy one current answer in USDC when a workflow needs it. The catalog includes agent-readiness audits, vendor onboarding risk, transaction preflight, live x402 opportunity research, company intelligence, endpoint verification, website due diligence, VIN safety, market checks, security research, and atomic EVM reads.

Every billable route accepts ?preview=true. The preview is a live contract proof showing the source, freshness, required inputs, and response shape. It deliberately withholds the decision-ready values delivered by the paid call.

Start with the free find_marketplace_products MCP tool. Give it the buyer's task in plain language and it returns three ranked live products plus one recommended_purchase containing the exact price, required inputs, and ready preview and paid-call payloads. Replace the example inputs with the buyer's real values, preview when available, and only use the paid call after the user authorizes the listed price and payment method.

Try it without a wallet

Open a live Shopify catalog preview. It runs the public source and shows the response contract; the complete catalog result remains behind the 0.01 USDC payment gate. No account, key, or payment is needed for the preview.

To try the MCP adapter in an existing client, copy the two-tool configuration and ask your agent: “Find a tool to check a public Shopify storefront. Show me its price and free preview; do not pay.” Compact mode keeps the full catalog behind two tools. The free integration check shows the same discovery and preview path end to end.

Want a runnable example for two common buyer tasks? Try Shopify catalog and TLS certificate previews. Both use the real production source with payment disabled.

The store publishes live, deduplicated settlement totals that separate external payments from owner-controlled tests. Paid API calls demonstrate use of the store; they are not a count of unique people or proof that each buyer installed this MCP package. npm download counts also include automated installs.

Related MCP server: CorteX402

Community spotlight: Grey Ridge Signals

Grey Ridge Signals offers a Base swap safety gate and token report that may complement DopamineDesk's token-audit and transaction-preflight tools. Explore their free swap gate preview or free token report preview.

These are independently operated Grey Ridge services, not DopamineDesk products. Review their current terms and prices before authorizing any paid request. We have tested a small number of free previews; their results are not a guarantee of safety.

Engineering overview

This repository contains the open-source MCP buyer adapter and client. The marketplace backend is a separate service.

flowchart LR
    A[MCP client] --> B[Local adapter]
    B --> C[OpenAPI discovery and free previews]
    B --> D[Opt-in capped payment]
    D --> E[Marketplace endpoint]
    E --> F[Result and settlement details]

The adapter derives tools from the service's OpenAPI contract, keeps signing keys local, and rejects disabled, conflicting, malformed, and over-cap payment requests. Inspect payment flow, client examples, and automated verification.

Install

npx -y dopaminedesk-ai-data-marketplace-mcp

Use it from any stdio-compatible MCP client:

{
  "mcpServers": {
    "dopaminedesk-data-marketplace": {
      "command": "npx",
      "args": ["-y", "dopaminedesk-ai-data-marketplace-mcp"]
    }
  }
}

Official MCP Registry name: io.github.jblaz6335/ai-data-marketplace.

Small tool list for existing agents

Set X402_TOOL_MODE=compact to expose just find_marketplace_products and purchase_marketplace_product. All live products remain available through those two tools. The default full mode keeps the product-specific tools for existing integrations.

No environment variable or wallet key is required to start the default server. A wallet is needed only if the buyer chooses locally signed auto-pay. The remote /mcp URL is a separate authenticated publisher integration, not the public stdio install URL.

Ready-to-copy configurations and a free end-to-end client check are in examples/README.md. The check discovers a real product and requests its free preview. It never signs or submits a payment.

Buy with credits instead of configuring a wallet

The service is already indexed in APIHub's external x402 catalog. Buyers with APIHub credits can ask its proxy to sign and settle a marketplace call without keeping a Base wallet or gas in the calling process:

npx @apihubio/cli register
npx @apihubio/cli topup 5
npx @apihubio/cli call https://ai-data-marketplace-1042299154756.us-central1.run.app/api/v1/evm_block_number

APIHub is an independent third party with its own account, credit, markup, and terms. Direct x402 remains the self-custody path. Both routes settle the protected endpoint before its paid result is delivered.

Inspect a live contract

curl "https://ai-data-marketplace-1042299154756.us-central1.run.app/api/v1/company_intelligence?preview=true&domain=example.com"

The proof includes source, freshness, request parameters, top-level fields, response shape, and a purchase block. Decision-ready values remain in the paid result.

Optional one-call purchasing

The current npm release can complete the x402 challenge, authorization, retry, and settlement automatically. Install the public package directly:

npx -y dopaminedesk-ai-data-marketplace-mcp

The buyer key stays inside the local MCP process and is never sent to the marketplace. Use a dedicated low-balance Base wallet, not a primary wallet.

{
  "mcpServers": {
    "dopaminedesk-data-marketplace": {
      "command": "npx",
      "args": ["-y", "dopaminedesk-ai-data-marketplace-mcp@2.11.3"],
      "env": {
        "X402_AUTO_PAY": "true",
        "X402_EVM_PRIVATE_KEY": "YOUR_DEDICATED_BUYER_WALLET_KEY",
        "X402_MAX_PAYMENT_USDC": "0.25"
      }
    }
  }
}

Call a product with auto_pay: true. The adapter refuses disabled, conflicting, invalid, or over-cap purchases. It never falls back to an uncapped payment.

For automated client installation, see llms-install.md. Its default configuration exposes free discovery and previews without collecting a wallet key or enabling automatic payment.

Verification and engineering scope

The public verification hub and machine verification record expose the production evidence.

I built this adapter around these constraints:

• the production OpenAPI contract is the source of truth for tool discovery;

• live contract proofs verify the source and schema without replacing the paid product;

• automatic purchasing is opt-in, locally signed, and protected by a hard per-call cap;

• conflicting, malformed, disabled, and over-cap payment attempts fail closed;

• settlement details stay attached to the delivered result for reconciliation.

Run the verification suite locally:

npm ci
npm test

Production contracts

• Store: https://ai-data-marketplace-1042299154756.us-central1.run.app/

• OpenAPI: https://ai-data-marketplace-1042299154756.us-central1.run.app/openapi.json

• Postman: https://ai-data-marketplace-1042299154756.us-central1.run.app/postman.json

• LLM manifest: https://ai-data-marketplace-1042299154756.us-central1.run.app/llms.txt

• x402 manifest: https://ai-data-marketplace-1042299154756.us-central1.run.app/.well-known/x402

• x402scan: https://www.x402scan.com/server/8dd63536-ba25-40f4-b36a-7d05ed18d007

The MCP adapter builds its tool list from the production OpenAPI document. Counts, prices, availability, data mode, and source declarations come from the live contract instead of a hand-written endpoint list.

Every billable product uses x402 v2 exact payments on Base mainnet through the Coinbase CDP facilitator:

1. Call the endpoint and read the base64 PAYMENT-REQUIRED response header.

2. Sign the exact authorization with a compatible x402 buyer client.

3. Retry with PAYMENT-SIGNATURE.

4. Read settlement details from PAYMENT-RESPONSE.

See PAYMENT_FLOW.md for the manual and legacy confirmed-transaction paths.

Buyer-ready outcomes

These are complete paid deliverables, not teaser text. The lower-level catalog remains available for workflows that need a single chain read, filing, sanctions check, quote, or verification result.

If this open-source buyer adapter saves you integration work, you can support its maintenance on Ko-fi.

Published distribution

• npm package

• Official MCP Registry

• Smithery

• x402scan

License

MIT License. Open-source MCP buyer adapter and marketplace client.