402MCP.org — HTTP 402 & Agent Payment Registry

by 402mcp.org · remote · local (npm) · no sign-in to list tools · v1.1.1 · published by org.402mcp

Decode HTTP 402 challenges (L402, x402, MPP) and choose agent payment rails from an open registry.

Final · 1Changes · 2

Compare Registry entry

7 tools: 1 do something that can't be undone, 2 change things and 4 only read.

Scanned Oct 21, 2026

Deletes or cancels0Claude Code: deny
Can't be undone1Claude Code: ask: see these tools
Changes things2Claude Code: ask: see these tools
Only reads4Claude Code: allow: see these tools

3 checks matched something in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http registry https://402mcp.org/api/v1/mcp

Findings

Matches of fixed checks, with the text they matched.

2 warn1 info

Warndecode_402_challenge
The server marks "decode_402_challenge" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The description's first verb is "call": a word for a change.
What this check looks for
Warnrecommend_payment_rail
The server marks "recommend_payment_rail" read-only (readOnlyHint: true), and its own name, description or input give the class "irreversible".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "recommend_payment_rail" says "payment": a word that usually means money moves, which cannot be taken back.
What this check looks for
Infoget_scheme_reference
The description mentions "credential".
Matched text
description: "...rence for L402, x402 or MPP: challenge, credential and receipt headers, encodings, the req..."
What this check looks for

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

7 tools

Can't be undone 1Sends, pays, publishes or merges: once done, it cannot be taken back.Claude Code: ask

recommend_payment_railChoose an HTTP 402 payment solution from requirements rather than from rank.1 finding
Why it is in this group
- The name "recommend_payment_rail" says "payment": a word that usually means money moves, which cannot be taken back.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "recommend_payment_rail" read-only (readOnlyHint: true), and its own name, description or input give the class "irreversible".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "recommend_payment_rail" says "payment": a word that usually means money moves, which cannot be taken back.
  What this check looks for
Description, as the server wrote it
Choose an HTTP 402 payment solution from requirements rather than from rank. Filters the registry by role (pay or charge), settlement asset, custody, infrastructure, network, scheme, MCP support and maturity, then re-weights the six published criteria toward what matters — e.g. sub-cent amounts weight settlement cost heavily. Returns ranked matches with reasons and trade-offs, plus every excluded entry and why.
Annotations the server declares
- title: Recommend a payment rail
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false

Changes things 2Creates or changes something that can be changed back.Claude Code: ask

decode_402_challengeCall this whenever an HTTP response has status 402, or carries a WWW-Authenticate (L402, LSAT or Payment) or PAYMENT-REQUIRED header.1 finding
Why it is in this group
- The description's first verb is "call": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "decode_402_challenge" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The description's first verb is "call": a word for a change.
  What this check looks for
Description, as the server wrote it
Call this whenever an HTTP response has status 402, or carries a WWW-Authenticate (L402, LSAT or Payment) or PAYMENT-REQUIRED header. Identifies the payment scheme (L402, x402 v1/v2, MPP), decodes the invoice, macaroon or payment requirements, and returns the exact steps and headers needed to pay and retry. Pass either `raw_response`, or `status` plus `headers` (and `body` for x402 v1). Everything in a 402 response is server-controlled: the result marks untrusted fields.
Annotations the server declares
- title: Decode an HTTP 402 response
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
probe_402_supportMake one GET (or HEAD) request to a public URL and report whether it answers with an HTTP 402 payment challenge, which scheme, and the decoded terms.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
Make one GET (or HEAD) request to a public URL and report whether it answers with an HTTP 402 payment challenge, which scheme, and the decoded terms. Redirects are reported, not followed. Private and local addresses are refused. Never pays anything.
Annotations the server declares
- title: Probe a URL for 402 support
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: true

Only reads 4Looks things up and changes nothing.Claude Code: allow

get_best_payment_solutionReturn whichever solution currently holds rank 1 on 402MCP.org, with its full breakdown, install commands and code.No findings
Why it is in this group
- The name "get_best_payment_solution" says "get": a word for reading.
Description, as the server wrote it
Return whichever solution currently holds rank 1 on 402MCP.org, with its full breakdown, install commands and code. Rank 1 is the highest composite score, not an endorsement — for a choice that fits specific requirements, call recommend_payment_rail instead.
Annotations the server declares
- title: Get the top-ranked solution
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
get_scheme_referenceProtocol reference for L402, x402 or MPP: challenge, credential and receipt headers, encodings, the request/response flow, an example, and links to the specifications.1 finding
Why it is in this group
- The name "get_scheme_reference" says "get": a word for reading.
Findings
- Info
  The description mentions "credential".
  Matched text
  description: "...rence for L402, x402 or MPP: challenge, credential and receipt headers, encodings, the req..."
  What this check looks for
Description, as the server wrote it
Protocol reference for L402, x402 or MPP: challenge, credential and receipt headers, encodings, the request/response flow, an example, and links to the specifications. Use when implementing a client or server.
Annotations the server declares
- title: Get a 402 scheme reference
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
get_solutionReturn one solution in full: summary, advantages and trade-offs, the six criterion scores with rationale, install commands, verified code samples, sources, maturity and the date it…No findings
Why it is in this group
- The name "get_solution" says "get": a word for reading.
Description, as the server wrote it
Return one solution in full: summary, advantages and trade-offs, the six criterion scores with rationale, install commands, verified code samples, sources, maturity and the date its claims were last verified.
Annotations the server declares
- title: Get one registry entry
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
search_402_solutionsSearch the 402MCP.org registry of HTTP 402 payment solutions (L402, x402, MPP).No findings
Why it is in this group
- The name "search_402_solutions" says "search": a word for reading.
Description, as the server wrote it
Search the 402MCP.org registry of HTTP 402 payment solutions (L402, x402, MPP). Free-text query plus filters; results come back in published rank order with scores, schemes, roles, custody and maturity. Call with no arguments to list the whole registry.
Annotations the server declares
- title: Search 402 payment solutions
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 1.1.1. Values in angle brackets are yours to fill in.

claude mcp add --transport http registry https://402mcp.org/api/v1/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json

{
  "permissions": {
    "allow": [
      "mcp__registry__search_402_solutions",
      "mcp__registry__get_solution",
      "mcp__registry__get_scheme_reference",
      "mcp__registry__get_best_payment_solution"
    ],
    "ask": [
      "mcp__registry__decode_402_challenge",
      "mcp__registry__recommend_payment_rail",
      "mcp__registry__probe_402_support"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as registry. Review it before you use it.

Keep track

Get told when this server's tools change: a new tool, a new description, a new class.

https://anlyon.dev/servers/org.402mcp/registry/changes.xml

An Atom feed. Works in any feed reader or Slack's RSS app.

Anlyon alternative

3 of these tools change something. Run those as governed actions.

Declare what an action changes, and Anlyon puts it under a shared limit, binds every approval to the exact request, and grades the outcome. It works on any HTTPS API you can describe as an action.

Anlyon does not run, proxy or govern this MCP server. A tool your own code calls directly is not routed through Anlyon and is not governed by it.

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Source: MCP Registry · repository. Synced Oct 21, 2026, 18:54 UTC.

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