Live Listing Proof MCP¶

Hosted verification service that checks a public listing before an agent relies on it. Send a URL and a claim; get a fail-closed verdict with source-supported facts — or an explicit removed, blocked, unreachable, unsupported, or insufficient-evidence state. Designed for agents that recommend products, cite listings, monitor classifieds, or act on advertised prices. $0.02 USDC per verification on Base via x402, no API key and no account.

Server type: Remote (Streamable HTTP MCP)
Auth: None (x402 micropayment per call)
Endpoint: https://live-listing-proof.mattskowronis.workers.dev/mcp
Verify endpoint: https://live-listing-proof.mattskowronis.workers.dev/v1/verify
Pricing: $0.02 USDC per verification (Base mainnet)
Category: Verification / Trust
Registry: dev.workers.mattskowronis.live-listing-proof/verify-listing
Built by: Skowron Works (skowronworks.com)

Why This Matters for Operators¶

The most expensive failure mode for commerce agents is confident hallucination: recommending a product that was delisted, citing a price that changed, or alerting on a classified that sold yesterday. Live Listing Proof converts that failure mode into a cheap, fail-closed check. Instead of an agent trusting its training-time memory of a listing, it verifies the live page and gets a structured verdict with evidence.

The fail-closed design is the point: the service returns explicit negative states (removed, blocked, unreachable, unsupported, insufficient-evidence) rather than inventing facts. Recommendation and citation workflows should proceed only on verified with claim_supported: true.

Tools & Capabilities¶

Tool	What it does
`verify_listing`	Checks a listing URL against a supplied claim: availability, price, and/or location
`source_status`	Fail-closed state: verified, removed, blocked, unreachable, unsupported, or insufficient-evidence
Structured output	`verdict`, `claim_supported`, `title`, `price`, `location`, `evidence`, `retrieval_method` — optional facts are null when unsupported

Installation¶

claude mcp add --transport http live-listing-proof https://live-listing-proof.mattskowronis.workers.dev/mcp

No key, no account. Payment is settled per call via x402 (HTTP 402 Payment Required) in USDC on Base mainnet.

Configuration¶

{
  "mcpServers": {
    "live-listing-proof": {
      "type": "http",
      "url": "https://live-listing-proof.mattskowronis.workers.dev/mcp"
    }
  }
}

Business Relevance¶

Shopping agents verify a product URL and advertised price before recommending
Classified monitors check that an ad is still current before alerting
Auction agents confirm a lot has not sold or been removed before bidding decisions
Research agents cite only source-supported listing facts
Procurement agents check a supplier or product page before continuing a workflow

Integration with CorpusIQ¶

CorpusIQ tracks the outcome; Live Listing Proof guards the input. A procurement or research agent can verify a supplier's public listing with Live Listing Proof, then run the financial picture through CorpusIQ (payments history, invoices, vendor spend) before recommending action. Together they shrink the two biggest agent-commerce risks: acting on stale listing data and acting without a financial picture.

Limitations¶

One verification per paid call; not a search engine or price-history database
Verifies public listing pages only; no merchant-owned inventory API access
Results are not cached as fresh — each call is a live check
Individual-developer service hosted on Cloudflare Workers; no SLA published
x402 payment rails still early-adopter territory