What is pay-x402-service?

A payment workflow for finding x402 services, checking their prices, and calling them after user-approved payment on Solana, a blockchain network.

Searching for paid HTTP or MCP services, inspecting payment requirements, and paying for and calling an approved endpoint.

It avoids paying unknown prices and keeps signing on the user's machine, with a per-call spending limit and optional confirmation.

pay-x402-service — Skill for Claude Code by nirholas/x402-payments-mcp

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add nirholas/x402-payments-mcp --skill pay-x402-service

Clone the repo

git clone --depth 1 https://github.com/nirholas/x402-payments-mcp

Made for: Claude Code.

Or install x402-payments-mcp, the plugin that ships this one along with the rest of its 1 skill, 1 MCP server.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/nirholas/x402-payments-mcp/pay-x402-service/github.svg)](https://agentmods.dev/skills/nirholas/x402-payments-mcp/pay-x402-service)

Your own site

<a href="https://agentmods.dev/skills/nirholas/x402-payments-mcp/pay-x402-service"><img src="https://agentmods.dev/badge/skills/nirholas/x402-payments-mcp/pay-x402-service/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/nirholas/x402-payments-mcp/pay-x402-service"><img src="https://agentmods.dev/badge/skills/nirholas/x402-payments-mcp/pay-x402-service.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 865 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00051	$0.00865
Opus 5.5	$0.00020	$0.00346
Sonnet 5.5	$0.00010	$0.00173
Haiku 4.5	$0.00005	$0.00086

Measured today against content hash 548607cfaf18, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

pay-x402-service scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/x402-payments-mcp/skills/pay-x402-service/SKILL.md · 42 lines

How it starts

The opening of the file, as written. The whole thing — 42 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Pay for an x402 service

The plugin starts @three-ws/x402-mcp over stdio (npx -y -p @three-ws/x402-mcp x402-mcp). Payments are signed on the user's machine with their own Solana key. There is no custodial wallet and no account.

Environment (export in the shell that starts Claude Code)

SOLANA_SECRET_KEY: base58 or JSON byte-array key that signs payments and holds the USDC. Only pay_and_call needs it. The user exports it themselves. Never ask for it in chat, never print it, never write it to a file.
SOLANA_RPC_URL (optional): Solana mainnet RPC, default is the public cluster.
MAX_PAY_USD (optional): per-call spend cap in USD, default 1.
REQUIRE_CONFIRM (optional): default on. While on, pay_and_call refuses until it is called again with confirm: true. Do not turn it off.
THREE_WS_BASE (optional): API origin for find_services, default https://three.ws.

Tools

Tool	Arguments	Spends money
`find_services`	`query`, `type` (`http` or `mcp`), `network` (CAIP-2, e.g. `solana:*`), `max_price_usdc`, `limit` (1-100)	No
`inspect_endpoint`	`url`, `method` (`GET`/`POST`), `body`	No. Returns the 402 requirements (schemes, networks, assets, price, pay-to) or the free result.
`x402_wallet`	`address` (optional, base58)	No. Reads the balance of the signer or a given address.
`pay_and_call`	`url`, `method`, `body`, `token` (`usdc` default, or `three`), `max_usd`, `confirm`, `idempotency_key`, `session_token`	Yes. A settled payment cannot be undone.

pay_and_call also accepts secret (a per-call signer) and session_token (a three.ws Payment Session token, pss_..., where the platform wallet pays under its own budget). Prefer the environment variable or a session token over passing a secret as an argument.

Procedure

find_services with a plain-language query to get candidates with prices and resource URLs.
inspect_endpoint on the chosen resource to see the exact price, asset and network.
Show the user the endpoint URL, the amount and the token (USDC, or $THREE when the endpoint advertises it). Stop and wait for an explicit yes.
pay_and_call with the URL, max_usd set to the approved amount, and no confirm. The first call refuses and tells you what it would do. Re-issue it with confirm: true only after the user said yes.
Report the result and the settlement details. Use the same idempotency_key when retrying a session-token call so it is not charged twice.

Read the full file on GitHub · 42 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

today First seen · 42 lines · 51 tokens per session scan A 548607cfaf18

Subscribe to this mod's changes

pay-x402-service is a skill published in the GitHub repository nirholas/x402-payments-mcp (9 stars, last pushed today), licensed Apache-2.0. It adds 51 tokens to every session and 865 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-11-11.

Finance and fintech Web3 and blockchain mcp mcp-server model-context-protocol payments solana x402

pay-x402-service next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
pay-x402-servicenirholas/x402-payments-mcp	Skill	9	today	Apache-2.0	A	51	Claude Code
x402-paymentsANAMIZED/OpenMesha	Skill	1	2mo ago	none	A	39	Claude Code, Codex
x402-listmcccsm/x402-list-mcp	Skill	18	29d ago	MIT	A	99	Claude Code, Codex
x402-paymentsANAMIZED/Server-OS	Skill	1	2mo ago	none	A	19	Claude Code, Codex
crypto-dataBlockRunAI/blockrun-mcp	Skill	390	yesterday	MIT	A	194	Claude Code, Codex
polymarket-tradingBlockRunAI/blockrun-mcp	Skill	390	yesterday	MIT	A	72	Claude Code, Codex
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