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x402check MCP server

Which MCP servers are x402check's own, from the official registry and from asking its own domain, whether they answer, and what they offer. A program checked each of these, nobody copied them from a product page.

read 2026-10-31

← Back to x402check

Whose server it is
  • Registry namedev.x402check/mcpverified in the MCP registry

The registry name sits under x402check.dev. The registry only lets a publisher use that namespace after proving control of the domain through DNS or HTTP.

When we asked itchecked 2026-10-31
  • Stateanswerschecked 2026-10-31
  • Tools4
  • Server calls itselfx402check
  • Server version0.2.2
  • Protocol version2024-11-05

On 2026-10-31 the server answered initialize and tools/list without a sign-in. First answer in 47 ms.

Should an agent connect itNot proven either way yet
  • Its tools do every use case we checked: verify a seller's payment address before signing; compare candidate x402 sellers by verdict and price; detect payment address or price changes on an endpoint.
  • Checked on 2 of the 7 days it takes to judge reliability.

Once connected

  • For "verify a seller's payment address before signing", the likely first call is verify_payto.
  • For "compare candidate x402 sellers by verdict and price", the likely first call is compare_tools.
  • For "detect payment address or price changes on an endpoint", the likely first call is preflight_check.
  • Parameters are untyped or undescribed in 2 of 4 tools: check arguments before calling.

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.

Measured dailydaily checks: 2, the first on 2026-10-31
  • INITE MCP scoreafter a weeka score needs 7 daily checks: 2 so far
  • What an agent can do with it3 of 3 use cases
  • Answeredmeasuring2 of the 7 daily checks it takes to print a share
  • Median first answer205 ms
  • Space in an agent's context≈ 605 tokensthe definitions of all its tools (4), which an agent carries on every turn
  • Tool definitionsA · 92 of 100
  • Typed results0 of 4 toolsdeclared outputSchema: results come typed, read once
  • Parameters without a description: in 2 of 4

What an agent can do with it

  • can do · verify a seller's payment address before signing
  • can do · compare candidate x402 sellers by verdict and price
  • can do · detect payment address or price changes on an endpoint

Each of the product's use cases, put to Jev against this server's tool list: can an agent do it with these tools?

Worth a look

None of the five warning signs in these definitions.

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 →

Tools it offers4 tools · read 2026-10-31
  • preflight_check

    Mandatory trust preflight before paying any x402 endpoint. Pass the absolute https seller URL. Returns verdict ok|caution|avoid plus that tool's history only (uptime, payToChanges, priceChanges). Use when: about to settle /…

  • verify_payto

    Verify the payTo / receiving wallet an x402 seller demands before you sign. Same check as preflight_check: live 402 probe + history.payToChanges (wallet rotations) and priceChanges. Use when confirming which Base USDC address you will…

  • preflight_batch

    Trust-check up to 25 x402 seller URLs in one request. Charged per URL (N × unit) in a single Exact settlement. Prefer when comparing candidates, picking the cheapest/most reliable, or screening Bazaar search hits before paying any of them.

  • compare_tools

    Compare several x402 tools before choosing which to pay. Alias of preflight_batch: returns each URL's verdict, priceUsd, payTo, uptimePct, and drift history so you can pick reliable/cheap candidates and skip avoid. Charged per URL.

How to connect

Add the server to your MCP client config. Claude Desktop, Cursor and most other clients read this shape:

{
  "mcpServers": {
    "x402check": {
      "type": "http",
      "url": "https://x402check.dev/mcp"
    }
  }
}

Add it

Claude Code, in a terminal

claude mcp add --transport http x402check https://x402check.dev/mcp

Add to CursorAdd to VS Code

claude.ai, ChatGPT and other clients: add https://x402check.dev/mcp as a custom connector in the settings.

Also shipped through: npm

OpenAPI spec

10 paths, read 2026-10-31. Open the spec ↗

Each line is something a program found when it went looking: the registry entry, the server's own answer, a spec that parses. A missing line means we did not find it, not that it does not exist.