What Agents Buy

com.whatagentsbuyPublished by whatagentsbuy.comOfficial publisherv1.0.1Updated Oct 24, 2026

Independent measured reviews of x402 API sellers: pre-payment verdicts and accuracy grades.

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Overview

AI-generated overview

A remote MCP server that gives assistants independent, measured reviews of x402 API sellers, including pre-payment safety verdicts and accuracy grades.

What you can do
Find payable x402 APIs for a described task, ranked by proven accuracy, payment safety and price, and look up a specific seller's full track record, quoted versus charged amounts and demand score. Get a single CLEAR, HOLD or ABORT verdict for a URL or host before paying, with an optional detailed payment-safety read. Rank sellers across the market by revenue or organic demand, and rank objective categories by how close returned values were to primary sources. Check x402 market size, recent Base settlement and 24-hour volume trends. Read field notes on known payment traps and how to avoid them.
When to use it
Useful when an assistant is about to pay an x402 API and needs a safety check, when choosing among payable APIs for a task, or when assessing how trustworthy a seller's numbers are. Also suited to questions about x402 market size and settlement activity.
Requirements
A remote streamable HTTP endpoint; no authentication, payment, environment variables or headers are declared. Network access to the endpoint is needed.
Before you install
The server itself takes no payment, but its verdicts and rankings are meant to gate real USDC payments made elsewhere, so a wrong or inconclusive verdict can cost money. Findings are described as independently measured and unsponsored, but they are third-party assessments; treat HOLD and inconclusive results as reasons to verify before paying.

Installation

In SourceWeft

  1. Open What Agents Buy in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/com.whatagentsbuy%2Fwhatagentsbuy/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "what-agents-buy": {
      "type": "http",
      "url": "https://whatagentsbuy.com/mcp"
    }
  }
}

README

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.
  • get_service, search_services, top_services, list_traps, market_summary.

Add it with:

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

Pipeline

fetch_registry.py    # discover the payable endpointssweep.py             # Base USDC settlement tape (sweep_solana.py for Solana)whatsnew.py          # registry diff, first-seen trackingprobe.py             # free directory probe: who answers, price/payTo honestyconform.py           # the paid-call chokepoint: archive raw, judge, reconcilelab.py               # daily accuracy corpus vs primary sourcesreceipts.py          # content-hashed, self-verifying dispute receiptsleaderboard.py       # settlement to a leaderboard + Organic Demand Scorepreflight.py         # the pre-payment verdict enginebuild.py             # everything to a static site

The *_shootout.py scripts buy the same thing from every seller in a category (email validation, gas, WHOIS, price, weather) and publish the contrast.

Tests

python3 tests.py            # pipeline invariants, fixture-based, no networknode --test api/*.test.js   # the MCP server

Both run in CI on every push, and tests.py runs at three gates locally: before every build, in the pre-commit hook, and before any script spends money.

Author

Neil K. Patel — neilkpatel.com · LinkedIn

Feedback and corrections are welcome on LinkedIn.

License

The measurements published on the site are CC BY 4.0 (attribute What Agents Buy). This code is shared for transparency and independent review of the methodology.

Source: README.md at commit 39b1b61

Tools

7

find_api

Find a payable API for a task

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.

Parameterstaskrequiredlimitmax_price_usdcmin_reliabilityallowed_verdicts

check_before_paying

The one check before your agent pays

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.)

Parametersurlrequireddetail

look_up_seller

Everything known about one seller

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.)

Parametershostrequired

rank_sellers

The leaderboard: biggest, or most real

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.)

Parametersbylimit

rank_by_accuracy

Who returns the most accurate value in a category

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.)

Parameterslimitcategory

market_size

How big is the x402 market

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.)

Takes no parameters.

known_payment_traps

How agents lose money paying APIs

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.)

Parametersquery

Version history

1
  1. v1.0.1LatestSep 16, 2026

Score

90% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts

    Declare a license in the repository or the registry entry.