x402Fetch

THE RISK

Critical Risk

Why x402Fetch needs a policy

This tool can autonomously spend USDC cryptocurrency to pay for HTTP resources. Any misuse or misdirection could result in financial loss, making it Financial category with critical severity since an AI agent could be tricked into making payments to arbitrary endpoints.

From the tool's definition automatically paying with USDC via x402 if the server requires payment

Documented attack patterns abuse exactly the kind of access x402Fetch gives an agent:

POLICY

How to control x402Fetch

PolicyLayer is an MCP gateway — it sits between your AI agents and Agentek Eth, and nothing reaches the server without passing your rules. This is the rule we recommend for x402Fetch:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "x402Fetch": {
      "deny_if": [
        {
          "conditions": [],
          "on_deny": "Requires human approval."
        }
      ]
    }
  }
}

Any call to x402Fetch is blocked until a human approves it. The rest of the server keeps working.

Create a free account and register Agentek Eth — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

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EXPLORE

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Go deeper

Critical-risk tools in Agentek Eth → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Human-in-the-loop → When a tool call should wait for a person — and when policy can decide alone.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
How to Add Spending Controls to Any MCP Agent →
Rate Limiting MCP Tool Calls: A Practical Guide →

FAQ

Questions about x402Fetch

What does the x402Fetch tool do? +

Fetch an HTTP resource, automatically paying with USDC via x402 if the server requires payment. Supports any x402-enabled API endpoint. It is categorised as a Financial tool in the Agentek Eth MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on x402Fetch? +

Register the Agentek Eth MCP server in PolicyLayer and add a rule for x402Fetch: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Agentek Eth. Nothing to install.

What risk level is x402Fetch? +

x402Fetch is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit x402Fetch? +

Yes. Add a rate_limit block to the x402Fetch rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block x402Fetch completely? +

Set action: deny in the PolicyLayer policy for x402Fetch. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides x402Fetch? +

x402Fetch is provided by the Agentek Eth MCP server (nanidao/agentek). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Agentek Eth tool call.

Start from Agentek Eth, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

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