x402-buyer-mcp
x402-buyer-mcp
x402エコシステムのためのユニバーサルバイヤーエージェント。
Claude Desktop、Cursor、Claude Codeのユーザーが、あらゆるx402エンドポイントを自動的に検索、支払い、呼び出しできるようにするMCPサーバーです。Claudeに質問すると、USDCで回答の対価を支払います。
Decixa(5,500以上の検証済みx402エンドポイント)による検索機能と、ローカルレジストリによるフォールバック機能を備えています。
インストール
Claude Desktop / Cursor
MCP設定に追加してください:
{
"mcpServers": {
"x402-buyer": {
"command": "npx",
"args": ["-y", "x402-buyer-mcp"]
}
}
}要件
Node.js 18以上
AgentCash ウォレットの設定と、Base上のUSDCによる資金供給
Related MCP server: signal402-mcp
ツール
ツール | 説明 |
| x402エンドポイントを検索 — Decixaの5,500以上の検証済みAPIをクエリし、ローカルフォールバックも利用 |
| AgentCashを介したUSDC自動支払いで、あらゆるx402エンドポイントを呼び出し |
| AgentCashウォレットの残高を確認 |
| マルチエンドポイント並列リサーチ — 3〜5つのエンドポイントを同時に呼び出し |
仕組み
Claudeに質問する(「stripe.comは安全ですか?」など)
x402_discoverがDecixaとローカルレジストリで一致するエンドポイントを検索x402_callがAgentCashを介してBase上のUSDCでエンドポイントに支払いデータが返され、Claudeが回答を統合
ローカルレジストリには、プレミアムソース(VirusTotal、People Data Labs、Hunter.io、AbuseIPDB、Qualys SSL Labs、NIH RxNorm、US Census、ESPN、The Odds API)に裏打ちされた8つのAlderpostインテリジェンスエンドポイントが含まれています。Decixaにより、検索範囲はx402エコシステム全体に広がります。
検索アーキテクチャ
プライマリ: Decixa /api/agent/resolve — 5,500以上の検証済みx402エンドポイントを対象としたセマンティック検索。レイテンシ、価格、信頼スコア、機能の一致度に基づいてランク付けされます。
フォールバック: 8つの厳選されたAlderpostエンドポイントのローカルレジストリ(完全なメタデータ付き)。Decixaに到達できない場合に自動的に使用されます。
この「ソフトスワップ」パターンにより、ネットワークがダウンしていても検索機能は常に動作します。
ローカルレジストリのエンドポイント
エンドポイント | 価格 | プレミアムソース |
Domain Shield | $0.12 | VirusTotal (70以上のエンジン) |
Company X-Ray | $0.15 | People Data Labs, Hunter.io |
Threat Pulse | $0.10 | VirusTotal, AbuseIPDB |
Compliance Check | $0.15 | Qualys SSL Labs |
Prospect IQ | $0.12 | People Data Labs, Hunter.io |
Sports Edge | $0.12 | ESPN, The Odds API, Claude AI |
Property Intel | $0.10 | US Census, OpenWeather |
Health Signal | $0.10 | NIH RxNorm, FDA |
変更履歴
v2.0.0
Decixa統合 — 検索時にDecixaの
/api/agent/resolveAPIをプライマリソースとしてクエリし、ローカルレジストリをフォールバックとして使用(ソフトスワップパターン)。x402_discoverがAlderpostエンドポイントだけでなく、x402エコシステム全体の結果を返すようになりました。自然言語クエリからDecixaの動詞ベースの分類体系への機能マッピングを追加。
エコシステム全体の検索を反映するようにツール説明を更新。
Decixaからの最初の統合パートナークレジット。
v1.0.5
npm binエントリとESMモジュール設定を修正。
CLIをルートの
cli.jsに移動。
v1.0.0
4つのツールと8つのAlderpostエンドポイントによる初期リリース。
クレジット
検索: Decixa — AIエージェントのための意思決定レイヤー
支払い: AgentCash — AIエージェントのためのUSDCウォレット
インテリジェンス: Alderpost — バンドルされたインテリジェンスAPI
リンク
ライセンス
MIT — Alderpost LLC
Available Tools
4 toolsx402_balanceA
Check your AgentCash USDC wallet balance on Base.
Returns current balance available for x402 payments and approximate number of calls you can afford. No parameters required.
If AgentCash is not set up, provides instructions to create and fund a wallet.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations provided, so description carries full burden. It accurately describes the read-only behavior, the information returned, and the fallback for unset wallets. No contradictions or hidden side effects noted.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three sentences, each providing essential info: purpose, return details, and fallback. No redundancy, perfectly front-loaded.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple balance check tool with no output schema, description covers all needed aspects: what it does, what it returns, and what happens if setup is missing. Context is fully complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Zero parameters and schema coverage 100%. Description reiterates no parameters are required, which adds no new info but is consistent. Baseline 4 is appropriate for zero-parameter tools.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description specifies the tool checks the AgentCash USDC wallet balance on Base, detailing what is returned (balance and approximate call count). It clearly distinguishes itself from siblings like x402_call (which likely makes payments) and x402_discover.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description states no parameters are needed and mentions setup instructions if missing. It implicitly conveys when to use (when you need balance info), but does not explicitly discuss when not to use or provide alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
x402_callA
Call any x402 paid API endpoint with automatic USDC payment via AgentCash.
Accepts a full URL with query parameters. Handles the complete x402 payment flow:
Sends request → receives 402 payment requirement
Signs USDC payment on Base via AgentCash wallet
Retries with payment proof → returns endpoint data
Requires AgentCash wallet to be set up and funded (https://agentcash.dev).
Examples:
url: "https://www.alderpost.co/api/domain-shield?domain=stripe.com"
url: "https://www.alderpost.co/api/company-xray?domain=hubspot.com"
url: "https://www.alderpost.co/api/health-signal?query=ibuprofen"
url: "https://www.alderpost.co/api/property-intel?address=123+Main+St+Milwaukee+WI"
Works with any x402 endpoint URL discovered via x402_discover.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | Full endpoint URL with query parameters |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Despite no annotations, the description fully discloses the 3-step payment flow, requirements for AgentCash wallet, and retry logic. No contradictions or hidden behaviors.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Well-structured with clear sections, bullet-point steps, and examples. Every sentence adds value; no redundancy.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given no output schema, the description lacks explicit return value details, but examples imply endpoint data. Overall, it covers purpose, flow, requirements, and usage adequately.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema covers the 'url' parameter with 100% coverage, and description adds examples and explains it accepts full URLs with query parameters, adding value beyond the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
Description clearly states it calls x402 paid APIs with automatic USDC payment. It distinguishes from siblings (x402_balance, x402_discover, x402_research) which handle different aspects of the x402 protocol.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Provides when-to-use context with examples and mentions integration with x402_discover. Lacks explicit when-not-to-use or alternative tools, but context is sufficient.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
x402_discoverA
Search for x402 paid API endpoints that can answer a question or provide data.
Discovery powered by Decixa (5,500+ verified x402 endpoints) with local registry fallback. Searches across the entire x402 ecosystem — not just Alderpost endpoints.
Local registry includes premium endpoints backed by VirusTotal, People Data Labs, Hunter.io, AbuseIPDB, Qualys SSL Labs, NIH RxNorm, US Census Bureau, OpenWeather, The Odds API.
Categories: security, company/business, threat intelligence, sales/leads, compliance, health/drug, property/location, sports, and any x402 capability indexed by Decixa.
Examples:
query "domain security" → finds Domain Shield + other x402 security scanners
query "company information" → finds Company X-Ray + other enrichment APIs
query "verify factual claims" → finds verification endpoints via Decixa
query "drug interactions" → finds Health Signal (NIH RxNorm)
Use x402_call to call any discovered endpoint.
| Name | Required | Description | Default |
|---|---|---|---|
| query | Yes | What data do you need? E.g. "domain security", "company revenue", "drug interactions", "verify a claim" |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It describes the tool as a read-only search across the ecosystem, mentions the fallback mechanism, and lists categories. No destructive behavior is indicated, and no contradictions are present.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is well-structured with bullet points and examples, front-loading the core purpose. While somewhat lengthy, every sentence adds value and the structure aids readability.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description lacks explicit details about the output format (e.g., what fields are returned). Given no output schema, this is a notable gap. However, the mention of x402_call for calling endpoints implies the tool returns endpoint details, and the examples suggest a list.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The single parameter 'query' has a clear description in the schema, and the tool description adds valuable examples and context (e.g., 'domain security' → finds Domain Shield). Schema coverage is 100%, so the description complements the schema well.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states it searches for x402 paid API endpoints, specifies the source (Decixa with local fallback), and distinguishes it from siblings like x402_call. Examples illustrate specific queries and expected results.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description tells when to use this tool (for discovery) and explicitly links to x402_call for calling endpoints. It provides query examples but does not explicitly state when not to use it or alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
x402_researchA
Run comprehensive research by calling multiple x402 endpoints in parallel.
Given a subject (domain, IP, address, drug name, or sport), this tool:
Detects the input type automatically
Finds all relevant x402 endpoints (local registry)
Calls up to 5 endpoints simultaneously with automatic payment
Returns all results combined for synthesis
This is the fastest way to get a complete intelligence picture on any subject.
Input types (auto-detected):
Domain "stripe.com" → calls security + company + threat + compliance + sales (~$0.64)
IP "8.8.8.8" → calls threat intelligence (~$0.10)
Address "123 Main St Milwaukee WI" → calls property/location (~$0.10)
Drug "ibuprofen" → calls health intelligence (~$0.10)
Sport "nba" → calls sports intelligence (~$0.12)
Set max_cost to control budget per research call (default: $1.00).
| Name | Required | Description | Default |
|---|---|---|---|
| subject | Yes | The subject to research: domain, IP, address, drug name, or sport | |
| max_cost | No | Maximum total cost in USD (default: 1.00). Cheapest endpoints called first. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It discloses parallel calling, automatic payment, and cost control via max_cost. However, it omits details like authentication requirements, error handling, rate limits, and potential side effects.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is well-structured with a clear main sentence, followed by bullet points and examples. It is concise yet informative, with no redundant sentences. Every part contributes to understanding the tool's functionality.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given no output schema or annotations, the description covers the essential aspects: input processing, parallel execution, and cost management. It lacks details on return format and error scenarios, but these are mitigated by the tool's simplicity and the combined results description.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema has 100% description coverage. The description significantly adds value by explaining the subject parameter's auto-detection behavior and providing concrete examples. For max_cost, it clarifies that cheapest endpoints are called first, which is not evident from the schema alone.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool's purpose: running comprehensive research by calling multiple x402 endpoints in parallel. It specifies the input types (domain, IP, address, drug, sport) and the workflow (auto-detection, endpoint selection, parallel calls). This distinguishes it from siblings like x402_call, which likely calls a single endpoint.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides clear usage context, including when to use (fastest way to get intelligence) and examples for each input type. However, it does not explicitly mention when not to use or compare with sibling tools like x402_call or x402_discover.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
4 tool updates
v2.0.0- First observed
x402_balance - First observed
x402_call - First observed
x402_discover - First observed
x402_research
TDQS
Scored across 4 tools
Each tool has a clearly distinct purpose: checking balance, making a single payment-supported call, discovering endpoints, and running parallel research. No overlap or ambiguity.
All tools follow the 'x402_<action>' pattern with consistent lowercase and underscores. The actions are all verbs except 'balance', which is a noun but commonly understood as a verb in API contexts.
Four tools are exactly appropriate for the server's purpose. Each tool is essential and none feel redundant or missing.
The tool surface covers the full workflow: discover endpoints, check balance, call an endpoint, and run multi-endpoint research. No obvious gaps for the stated purpose of interacting with x402 APIs.
Maintenance
Related MCP Connectors
Let an AI agent find and pay for x402 APIs and products in USDC on Base, within owner-set limits.
x402-paid agent tools: 18 over HTTP, 14 over stdio. USDC per call, no API key.
Pay-per-call agent tools over x402 (USDC on Base) — no signup or API key.
Pay-per-call tools for autonomous agents, settled in USDC on Base via x402.
Related MCP Servers
- AlicenseNot gradedqualityDmaintenanceDiscovers and queries x402-payable APIs at runtime — enables autonomous agents to find, evaluate, and pay for services via USDC micropayments on Base without API keys or subscriptions.MIT
- FlicenseNot gradedqualityFmaintenanceEnables AI agents to discover, evaluate, and call any x402 API service with automatic USDC payment, including tools for wallet setup, service catalog browsing, recommendations, health checks, and direct API calls.8 npm-

@hpp-io/x402-mcp-bridgeofficial
AlicenseNot gradedqualityBmaintenanceEnables AI agents to autonomously pay for and discover services using HPP USDC.e over the x402 protocol, without API keys or manual signing.170 npmApache 2.0- AlicenseNot gradedqualityCmaintenanceThe open marketplace for the agent economy — Buy any of 24,000+ live x402 services with USDC on Base.6MIT