MCP.Market

What Agents Buy MCP server

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by whatagentsbuy.com·com.whatagentsbuy/whatagentsbuy·v1.0.1
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Independent measured reviews of x402 API sellers: pre-payment verdicts and accuracy grades.

A87/100grade A
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What Agents Buy tools (7)

write = sends, deletes, buys or posts
  • check_before_payingFree

    USE WHEN your agent is about to pay an x402 API and you want to know if it is safe and worth it. Returns one verdict for a URL or host in the `verdict` field (gate on that; `light` is the same decision as a colour, for display): CLEAR (nothing alarming), HOLD (pay but resolve the reasons), ABORT (do not pay without checking the live 402), UNRATED (no data). Also returns a confidence tier (verified = a payment to this seller settled AND produced a gradeable result, checked = free probe measured) and its payment history. Folds live price and payTo honesty, phantom paywalls, delivery receipts, and the wash/real-demand read into that one light. Pass detail:true for the full read. Whatever it says, still read the payTo and amount out of the live 402 and sign against those. (Formerly named preflight.)

  • find_apiFree

    USE WHEN you need an API that does something and want payable options. Searches the whole x402 market for what you describe and returns a ranked, pre-vetted shortlist, proven-accurate sellers first, then payment-safety, then price. Covers every reachable endpoint, not just ones we have bought from. Next step: check_before_paying on your pick, then read the payTo from the live 402 and sign against it.

  • known_payment_trapsFree

    USE WHEN writing payment code, or before trusting an unfamiliar seller. The field notes: each is a specific way an agent paying an API loses money or is misled, what it cost to learn, and what to do instead. (Formerly named list_traps.)

  • look_up_sellerFree

    USE WHEN you have a specific seller host and want its full track record. Returns every grade earned by actually paying it, what was quoted versus charged, whether goods arrived, its settlement volume, and its Organic Demand Score with the demand-shape read (is the volume real independent demand, or one wallet supplying almost all of it). The deep dossier on one seller; for a quick go/no-go before paying, use check_before_paying instead. (Formerly named get_service.)

  • market_sizeFree

    USE WHEN asked how big x402 is, whether it is growing, or what settled recently. Returns both what actually settled on Base over the last day (from chain logs, per tracked seller) and the live market pulse (24h volume and payments with day-over-day change, a 7-day series, and stablecoin circulation). All measured from chain, not registry counters, which are not demand and can be bought. (Merges the former market_summary and market_pulse.)

  • rank_by_accuracyFree

    USE WHEN a category has an objective right answer (crypto-price, stock-price, fx-rate, gas-price, wallet-balance, weather) and you want the sellers we PAID ranked by how close their returned value was to a primary source that cannot be a reseller (exchange median, chain balanceOf, ECB rates, FMP quote). Top rows are the cheapest accurate sellers. Call with no category to list the available ones. (Formerly named most_accurate.)

  • rank_sellersFree

    USE WHEN you want a ranked list of sellers across the market. by='revenue' ranks by raw USDC received (who is busy); by='real_demand' ranks by Organic Demand Score (whose money comes from many independent wallets rather than one wallet supplying almost all of it). The two disagree often, and the disagreement is the point. For accuracy ranking within an objective category, use rank_by_accuracy. (Formerly named top_services.)

Public scan report

scanner v0.1.10 · 2026-11-03 · same rubric, same numbers if you re-run it

no findings
  • –Code scanremote-only server, no package to scann/a
  • Live reliabilityremote reachable in 1159ms20/20
  • Tool poisoning7 tool descriptions checked15/15
  • Auth qualityopen endpoint, read-only tools10/15
  • Maintenancelast push 55 days ago12/15
  • Maintainer identityendpoint served from the registry-verified namespace domain8/10
Overall 87/100. Components that don't apply are left out of the denominator. Any critical finding is an F.RubricAppeal a findingJSON

How What Agents Buy compares

Against every graded Finance MCP server, from our own scans and uptime checks. Updated after each scan run.

Safety score
87/100
higher than 83% of 1,761 Finance servers
Tools
7
the typical Finance server has 8
Tools that change things
0%
typical: 0%. Fewer write tools means less an agent can break
Uptime
100%
of our recent checks; the typical remote Finance server answers 100%
Response time
230 ms
faster than 61% of 1,133 Finance servers

What its tools let an agent do: 6 read · 1 change

Install What Agents Buy in Claude Code, Cursor or VS Code

claude mcp add --transport http whatagentsbuy https://whatagentsbuy.com/mcp
Add to Cursor

What the publisher says

From the What Agents Buy repository's README, as published. We do not edit it. Read it on GitHub

What Agents Buy

Independent, measured reviews of the x402 APIs that AI agents pay for.

Live at whatagentsbuy.com · MCP server at https://whatagentsbuy.com/mcp · listed in the official MCP Registry as com.whatagentsbuy/whatagentsbuy.

Most numbers quoted about agentic payments come from registries and press releases, and they are wrong by orders of magnitude. This project measures the market directly. It pays x402 endpoints with a real wallet and publishes the receipt (what was quoted, what was actually charged, whether the goods arrived), sweeps every USDC payment agents make on Base straight off the chain, and grades the number a seller returns against a primary source that cannot be a reseller. Nothing is sponsored. No service pays to appear or to be graded.

This repository is the open methodology: the measurement pipeline and the agent-facing MCP server. The accumulated settlement history and the archive of paid responses stay private; everything they produce is published on the site.

What it measures

  • Settlement. USDC Transfer logs on Base, addressed to the payment wallet each service declares in its own x402 challenge. Measured from the chain, not from a registry's self-reported counters, which have been wrong by 30x. (sweep.py, leaderboard.py)
  • Delivery. Every graded call is a paid call. A field counts as delivered only if it is actually present in the response, checked against the seller's own schema, and every short verdict is re-verified with a second independent call before it is recorded. (conform.py, receipts.py)
  • Accuracy. For categories with an objective ground truth (crypto price, stock quote, FX rate, gas, wallet balance, weather), the number a seller returns is graded against a primary source that cannot be a reseller: an exchange median, a professional feed, the ECB, the chain itself. (lab.py, categorize.py)
  • Preflight. One CLEAR / HOLD / ABORT verdict per seller, folding live price and payTo honesty versus the listing, phantom paywalls, and delivery receipts into a single signal an agent can gate a payment on. A red light fires only from hard evidence. (preflight.py)

Every harsh finding is verified before it is published. Several early accusations turned out to be measurement bugs in this code, so the pipeline runs known-good canaries before it grades anyone, treats "we could not measure it" as inconclusive rather than a negative verdict, and re-verifies every shortfall twice.

The MCP server

api/mcp.js is a stateless, dependency-free MCP server (streamable HTTP, no auth, no payment) that exposes the measurements as tools an agent calls before it pays:

  • preflight(url) — the one pre-payment verdict; detail:true adds the full payment-safety read.
  • find_api(task) — discover a payable API for a task, proven-accurate sellers ranked first.
  • most_accurate(category) — rank an objective category by how close each seller's returned value is to a primary source.
  • getservice, searchservices, topservices, listtraps, market_summary.

Add it with:

claude mcp add --transport http whatagentsbuy https://whatagentsbuy.com/mcp

Pipeline

fetch_registry.py    # discover the payable endpoints
sweep.py             # Base USDC settlement tape (sweep_solana.py for Solana)
whatsnew.py          # registry diff, first-seen tracking
probe.py             # free directory probe: who answers, price/payTo honesty
conform.py           # the paid-call chokepoint: archive raw, judge, reconcile
lab.py               # daily accuracy corpus vs primary sources
receipts.py          # content-hashed, self-verifying dispute receipts
leaderboard.py       # settlement to a leaderboard + Organic Demand Score
preflight.py         # the pre-payment verdict engine
build.py             # everything to a static site

Shortened. The full README is on GitHub.

Nothing above is checked by us. What we check is on the safety report.

What Agents Buy: common questions

Is What Agents Buy MCP server safe?
Yes, by our scan: it is graded A (87/100). Read the What Agents Buy safety report
How do I install What Agents Buy?
It runs remotely at whatagentsbuy.com. Add it to Claude Code, Cursor, VS Code or Claude Desktop with the snippets above, or call it through the mcp.market gateway without installing anything.
Does What Agents Buy need an API key?
Not as far as the registry entry and our scan can tell: no credentials are declared or required.
Is What Agents Buy maintained?
The last commit was 56 days ago (2026-09-09). The latest release is v1.0.1.
Is What Agents Buy up?
100% of our last 28 checks got an answer. We check remote servers about four times a day.
What can I use instead of What Agents Buy?
Servers from other publishers that do the same job: three.ws Agent Payments MCP server, X402 List MCP server and ru-marketplace-mcp server.
How does What Agents Buy compare with other Finance MCP servers?
safety score 87/100 (higher than 83% of 1,761 Finance servers); tools 7 (the typical Finance server has 8); tools that change things 0% (typical: 0%. Fewer write tools means less an agent can break). Full comparison.

Alternatives to What Agents Buy

Same job from other publishers: the closest match first, then the best rated.

  • three.ws Agent Payments
    Governed x402 payment sessions: pay any endpoint with budget, allowlist & per-tx caps, no key.
    More from nirholas →
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  • X402 List
    Find and vet x402 payment APIs before your agent pays one: uptime, price, on-chain volume.
    A
  • ru-marketplace-mcp
    Read-only MCP servers for Russian marketplaces: prices, stock, ratings, reviews, seller identity
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  • Pulsefeed X402
    Verify x402 payment endpoints before an AI agent pays: scam scan, on-chain checks, trust scores.
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  • Blockrun
    Web search, deep research, prediction markets & crypto data for AI agents. Pay per call via x402.
    B