Yes, Anchor X402 is free to use.

How do I install Anchor X402?

Anchor X402 is a local plugin. Install it using npm package: anchor-x402-mcp and add the generated configuration snippet to your AI app's MCP config file. Then restart your AI app.

What credentials does Anchor X402 need?

Anchor X402 requires the following credentials or environment variables: ANCHOR_WALLET_PRIVATE_KEY. You can find setup instructions on the server detail page.

What AI apps work with Anchor X402?

Anchor X402 uses the Model Context Protocol (MCP) and works with any MCP-compatible AI app, including Claude, ChatGPT / Codex, Gemini, Copilot, Cursor, and more.

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Anchor X402 MCP Server

by Hypeprinter007 Stack

Developer ToolsModerate5.8MCP RegistryLocal

Free

Server data from the Official MCP Registry

14-tool x402 MCP: 9 onchain primitives + 5 LLM endpoints. USDC pay-per-call on Base or Solana.

About

14-tool x402 MCP: 9 onchain primitives + 5 LLM endpoints. USDC pay-per-call on Base or Solana.

Security Report

5.8

Moderate5.8Moderate Risk

This MCP server is well-designed for its specific purpose of payment-enabled blockchain API access. It properly handles private key credentials via environment variables, implements sound error handling for payment failures, and demonstrates no data exfiltration or dangerous code patterns. The permission model (network HTTP access, environment variable reading) is appropriate for a blockchain service client. Minor code quality improvements around input validation and error categorization are recommended, but do not constitute security vulnerabilities. Supply chain analysis found 2 known vulnerabilities in dependencies (0 critical, 2 high severity). Package verification found 1 issue.

3 files analyzed · 6 issues found

Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.

Permissions Required

This plugin requests these system permissions. Most are normal for its category.

env_vars

Check that this permission is expected for this type of plugin.

HTTP Network Access

Connects to external APIs or services over the internet.

What You'll Need

Set these up before or after installing:

EVM private key (0x-prefixed hex). The wallet pays for x402 calls in USDC on Base mainnet. Fund with USDC before use.Required

Environment variable: ANCHOR_WALLET_PRIVATE_KEY

How to Install

Add this to your MCP configuration file:

{
  "mcpServers": {
    "io-github-hypeprinter007-stack-anchor-x402": {
      "env": {
        "ANCHOR_WALLET_PRIVATE_KEY": "your-anchor-wallet-private-key-here"
      },
      "args": [
        "-y",
        "anchor-x402-mcp"
      ],
      "command": "npx"
    }
  }
}

Documentation

View on GitHub

From the project's GitHub README.

anchor-x402-mcp

MCP server exposing 14 anchor-x402 services as tools any Claude Desktop / Cursor / Codex / Continue agent can call. Pay-per-use USDC via x402 on Base mainnet — no API keys, no subscriptions.

What an agent gets

Fourteen tools, $0.001–$0.05 per call.

Commodity primitives (9, $0.001–$0.010):

Tool	Price	What it does
`anchor_hash`	$0.005	Anchor any 32-byte hash to Base + Solana mainnet in parallel; returns both tx URLs
`screen_wallet`	$0.001	OFAC SDN sanctions screening for any EVM or Solana wallet
`attest_decision`	$0.010	Verify a wallet signature over (input_hash, output_hash, decision); dual-chain anchor the result
`decode_tx`	$0.001	Structured decode of any mainnet tx (Base / Ethereum / Solana)
`resolve_name`	$0.001	Cross-chain name resolution (ENS, Bonfida SNS)
`token_price`	$0.001	USD spot price for any token by symbol or chain+contract
`decode_calldata`	$0.001	4byte selector + ABI param decode for raw EVM calldata
`parse_datetime`	$0.001	Freeform datetime string → structured ISO 8601
`intel_wallet`	$0.005	Bundled wallet intelligence: balances + activity + identity + sanctions in one call

Universal LLM endpoints (5, $0.01–$0.05) — added in v0.2:

Tool	Price	What it does
`roast`	$0.05	Witty 3-5 paragraph roast of any target — wallet, tweet, code, idea, anything
`oracle`	$0.05	Yes/no oracle. Returns YES/NO/MAYBE + reason + dual-chain anchored `(question \| answer \| timestamp)` hash. Cryptographic receipt of when you asked.
`tldr`	$0.01	Summarize a URL (fetches up to 500KB) or pasted text into 3-5 concise bullets
`aura`	$0.01	Returns color, tier (S/A/B/C/D/F), score 0-9999, and a punchy 2-3 sentence aura read
`grade`	$0.01	Academic letter grade (A+ to F) with red-pen marginalia and one-paragraph summary

The investigator (/v1/investigate, $7.77 async) and the hosted chatbot at chat.anchor-x402.com are not included in the MCP — they're accessed directly via the HTTP API and the browser respectively.

The MCP server pays for itself — your wallet gets debited automatically for each call. No prepay, no API key, no account.

Install

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "anchor-x402": {
      "command": "npx",
      "args": ["-y", "anchor-x402-mcp"],
      "env": {
        "ANCHOR_WALLET_PRIVATE_KEY": "0xYOUR_BASE_WALLET_PRIVATE_KEY"
      }
    }
  }
}

Restart Claude Desktop. Ask: "Anchor the hash 7646dda1564bde0ef3f3971f4c002962df64246da4aa1d8c47247e7632494710 on mainnet" — it'll call anchor_hash and pay $0.005 USDC from your wallet.

Claude Code

Add to your project's .mcp.json:

{
  "anchor-x402": {
    "command": "npx",
    "args": ["-y", "anchor-x402-mcp"],
    "env": {
      "ANCHOR_WALLET_PRIVATE_KEY": "0xYOUR_BASE_WALLET_PRIVATE_KEY"
    }
  }
}

Codex CLI (OpenAI)

Edit ~/.codex/config.toml:

[mcp_servers.anchor-x402]
command = "npx"
args = ["-y", "anchor-x402-mcp"]

[mcp_servers.anchor-x402.env]
ANCHOR_WALLET_PRIVATE_KEY = "0xYOUR_BASE_WALLET_PRIVATE_KEY"

Restart codex. Type /mcp to confirm anchor-x402 shows in the loaded servers list.

ChatGPT Desktop

Settings → Integrations → MCP servers → Add server. Paste:

{
  "command": "npx",
  "args": ["-y", "anchor-x402-mcp"],
  "env": {
    "ANCHOR_WALLET_PRIVATE_KEY": "0xYOUR_BASE_WALLET_PRIVATE_KEY"
  }
}

Save, restart, the 9 tools appear in any chat with tool-use enabled.

Cursor

Edit ~/.cursor/mcp.json (global) or <project>/.cursor/mcp.json (project-scoped):

{
  "mcpServers": {
    "anchor-x402": {
      "command": "npx",
      "args": ["-y", "anchor-x402-mcp"],
      "env": {
        "ANCHOR_WALLET_PRIVATE_KEY": "0xYOUR_BASE_WALLET_PRIVATE_KEY"
      }
    }
  }
}

OpenAI Agents SDK (programmatic)

from openai_agents import Agent, MCPServerStdio

mcp = MCPServerStdio(
    command="npx",
    args=["-y", "anchor-x402-mcp"],
    env={"ANCHOR_WALLET_PRIVATE_KEY": "0xYOUR_BASE_WALLET_PRIVATE_KEY"},
)
agent = Agent(name="researcher", model="gpt-4o", mcp_servers=[mcp])

Same package, same env, programmatic instead of config-driven.

Continue / Smithery / generic MCP client

Same shape — command: npx, args: [-y, anchor-x402-mcp], env carries your wallet key. The MCP SDK handles transport.

Or install via Smithery one-liner:

npx -y @smithery/cli install anchor-x402-mcp --client claude

(replace --client claude with cursor, codex, windsurf, etc.)

Run standalone

ANCHOR_WALLET_PRIVATE_KEY=0xYOUR_KEY npx anchor-x402-mcp

Speaks MCP over stdio. Pipe into any MCP-compatible client.

Funding your wallet

The wallet you set as ANCHOR_WALLET_PRIVATE_KEY needs USDC on Base mainnet. Any amount works — even $1 buys 100 anchor calls or 1000 commodity-tier calls. Send USDC to your wallet's Base address:

USDC contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
Bridge from Ethereum mainnet via bridge.base.org
Buy directly on Coinbase and withdraw to Base

The MCP server signs payments via x402 — Coinbase's open HTTP-native micropayments protocol. Each request:

Hits an anchor-x402 endpoint
Gets a 402 with payment requirements
Server signs a USDC transfer authorization with your private key
Retries the request with the signed payment — the API settles via Coinbase's facilitator

You see the response, your wallet's USDC balance ticks down by the call price. Sub-second, no ledger, no account.

Environment variables

Variable	Required?	Purpose
`ANCHOR_WALLET_PRIVATE_KEY`	Yes for paid calls	EVM private key. The wallet pays for x402 calls.
`ANCHOR_API_URL`	No	Override the API base URL. Default: `https://api.anchor-x402.com`. Useful for development against a self-hosted fork.

If ANCHOR_WALLET_PRIVATE_KEY is unset, paid tool calls return a friendly 402 message explaining how to set it. /health and /openapi.json (not exposed as tools, but reachable via direct curl) work without payment.

Security notes

The private key lives in your MCP client's config file. Treat it like a hot wallet — only fund what you're willing to spend autonomously.
Recommended: generate a fresh wallet specifically for agent use. Top up periodically; don't reuse a wallet that holds significant funds.
The MCP server only signs USDC payment authorizations to anchor-x402's known treasury addresses (visible in the 402 response). It cannot drain your wallet to arbitrary addresses.
Source code is fully open at github.com/hypeprinter007-stack/anchor-x402-mcp. Audit before installing.

Verifying anchor receipts

Every anchor_hash and attest_decision call returns Base + Solana tx URLs. These are independently verifiable on the public block explorers — agents can confirm an anchor exists without re-paying:

Base: https://basescan.org/tx/<base.tx> — Input Data field contains the merkle root
Solana: https://solscan.io/tx/<solana.tx> — Memo program data contains the same hex

The on-chain bytes are the receipt; the API response is just a convenience wrapper around them. See the on-chain verifiability primer for the full verification recipe.

Troubleshooting

"Payment required (402). Set ANCHOR_WALLET_PRIVATE_KEY..." You haven't configured a wallet. Add the env var to your MCP config and restart Claude Desktop.

"Payment failed (402). The wallet may be out of USDC..." Your wallet ran out. Send USDC on Base to the wallet address shown in the server's startup log (it logs payer=0x… to stderr).

"anchor-x402 request failed: ..." Network or DNS issue. Check https://api.anchor-x402.com/health returns 200; if not, see the status page.

License

MIT

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Anchor X402 MCP Server

About

Security Report

Findings (6)Action required

Permissions Required

What You'll Need

How to Install

Documentation

anchor-x402-mcp

What an agent gets

Install

Claude Desktop

Claude Code

Codex CLI (OpenAI)

ChatGPT Desktop

Cursor

OpenAI Agents SDK (programmatic)

Continue / Smithery / generic MCP client

Run standalone

Funding your wallet

Environment variables

Security notes

Verifying anchor receipts

Troubleshooting

Links

License

Reviews

No reviews yet

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