What Agents Buy MCP server

• Registry namecom.whatagentsbuy/whatagentsbuyverified in the MCP registry

The registry name sits under whatagentsbuy.com. The registry only lets a publisher use that namespace after proving control of the domain through DNS or HTTP.

• Stateanswerschecked 2026-10-25
• Tools7
• Server calls itselfwhatagentsbuy
• Server version1.1.0
• Protocol version2025-06-18

On 2026-10-25 the server answered initialize and tools/list without a sign-in. First answer in 297 ms.

• Its tools do every use case we checked: gate agent payments with a preflight check before paying; see which x402 sellers are getting paid real demand.
• Checked on 1 of the 7 days it takes to judge reliability.

Said by rules from the measurements above. The likely first call is a model's pick from the tool list; read its description before relying on it.

• INITE MCP scoreafter a weeka score needs 7 daily checks: 1 so far
• What an agent can do with it2 of 2 use cases
• Answeredmeasuring1 of the 7 daily checks it takes to print a share
• Median first answer428 ms
• Space in an agent's context≈ 1,375 tokensthe definitions of all its tools (7), which an agent carries on every turn
• Tool definitionsB · 81 of 100
• Typed results0 of 7 toolsdeclared outputSchema: results come typed, read once

• Parameters without a description: in 1 of 7
• Not saying whether it only reads or can destroy: 7 of 7

A program checks the server once a day: initialize and tools/list, no model. Tokens are the definitions' length at about four characters a token. The grade averages six checks of every tool's name, description, schema and annotations; it says how well the tools are described, not whether they work. The score weighs what was measured and nothing else: answering (25%), doing the product's job (25%), definitions (20%), context (10%), use (10%) and how readily a client connects (10%). A part that was not measured is left out, and a hidden instruction caps the score at 40. The state of vendors' MCP servers: method and numbers →

• find_api

  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…

• check_before_paying

  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…

• look_up_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…

• rank_sellers

  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…

• rank_by_accuracy

  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…

• market_size

  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…

• known_payment_traps

  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.)