Probe a public x402 paid endpoint without signing or paying, then parse the HTTP 402 challenge. Pass target plus optional expected network/asset/price to verify payment metadata and receive a deterministic health receipt.
Part of the Boundary Guard x402 server.
Free to start. No card required.
AI agents call probe_x402_paid_path to retrieve information from Boundary Guard x402 without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though probe_x402_paid_path only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"probe_x402_paid_path": {}
}
}See the full Boundary Guard x402 policy for all 6 tools.
These attack patterns abuse exactly the kind of access probe_x402_paid_path gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Probe a public x402 paid endpoint without signing or paying, then parse the HTTP 402 challenge. Pass target plus optional expected network/asset/price to verify payment metadata and receive a deterministic health receipt.. It is categorised as a Read tool in the Boundary Guard x402 MCP Server, which means it retrieves data without modifying state.
Register the Boundary Guard x402 MCP server in PolicyLayer and add a rule for probe_x402_paid_path: 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 Boundary Guard x402. Nothing to install.
probe_x402_paid_path is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the probe_x402_paid_path 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.
Set action: deny in the PolicyLayer policy for probe_x402_paid_path. 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.
probe_x402_paid_path is provided by the Boundary Guard x402 MCP server (https://x402-resource-scanner.vercel.app/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 6 Boundary Guard x402 tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.