buy_pt

THE RISK

Critical Risk

Why buy_pt needs a policy

This tool executes a financial transaction on a DeFi protocol (Pendle), purchasing Principal Tokens which involves committing funds from the wallet. It moves crypto assets in exchange for fixed-yield instruments, constituting a financial commitment that cannot be trivially reversed without additional market operations.

From the tool's definition Buy PT (Principal Token) from a Pendle market for fixed yield at maturity

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

POLICY

How to control buy_pt

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

policy.json

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

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

Create a free account and register Waiaas — 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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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.
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FAQ

Questions about buy_pt

What does the buy_pt tool do? +

Buy PT (Principal Token) from a Pendle market for fixed yield at maturity. It is categorised as a Financial tool in the Waiaas MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on buy_pt? +

Register the Waiaas MCP server in PolicyLayer and add a rule for buy_pt: 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 Waiaas. Nothing to install.

What risk level is buy_pt? +

buy_pt 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 buy_pt? +

Yes. Add a rate_limit block to the buy_pt 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 buy_pt completely? +

Set action: deny in the PolicyLayer policy for buy_pt. 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 buy_pt? +

buy_pt is provided by the Waiaas MCP server (minhoyoo-iotrust/waiaas). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Waiaas tool call.

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

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