Keyless hosted MCP: pre-signature x402 payment verdict (GO/HOLD/STOP) with a signed receipt.
Install
Run one of the commands below, then add the client config underneath.
https://mcp.blackwalltier.comClient configuration
Paste into Claude Desktop, Cursor (mcp.json), VS Code or any MCP client, then restart the client.
{
"mcpServers": {
"blackwall-x402-guardrail": {
"url": "https://mcp.blackwalltier.com"
}
}
}About this server
Blackwall X402 Guardrail is listed in the Finance & Payments category of the MCPNav directory. It is distributed as Streamable HTTP and can be loaded by any client that speaks the Model Context Protocol.
Typical uses include giving your assistant scoped access to the corresponding service so it can answer questions and take actions with real data instead of guessing. Always review what a server can access before you enable it — see our MCP security guide.
Frequently asked questions
What is the Blackwall X402 Guardrail MCP server?＋
Blackwall X402 Guardrail is an MCP server by blackwalltier. Keyless hosted MCP: pre-signature x402 payment verdict (GO/HOLD/STOP) with a signed receipt.
How do I install Blackwall X402 Guardrail?＋
Install it with: https://mcp.blackwalltier.com. Then add the JSON config to your client's MCP settings and restart the client.
Is Blackwall X402 Guardrail free to use?＋
The MCP server itself is free to install. The source is public on https://github.com/bluetieroperations-create/blackwall-x402-mcp. Any third-party API it calls (such as a search or maps API) may require its own key and billing.
Which clients support Blackwall X402 Guardrail?＋
Any MCP-compatible client can use it, including Claude Desktop, Cursor, VS Code, Windsurf and custom agents.