kelly_size · Polymarket MCP Server MCP: Risk & Policy

WHAT IT DOES

What kelly_size does on Polymarket MCP Server

AI agents use kelly_size to commit financial operations through Polymarket MCP Server — usually the final step of a payment, billing, or trading workflow. A call moves real money.

WHY IT NEEDS A POLICY

Why kelly_size needs a policy

The Kelly criterion is a formula used to determine optimal bet/investment sizing. While this tool likely only calculates and returns a recommended bet size rather than directly executing a financial transaction, it provides direct financial advice that commits a user to specific financial obligations when acted upon.

From the tool's definition Calculate Kelly criterion bet sizing

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

kelly_size Approval-gated

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

View as policy code

policy.json

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

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Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Polymarket MCP Server, so you can run agents against it safely.

FAQ

Questions about kelly_size

What does the kelly_size tool do? +

Calculate Kelly criterion bet sizing. It is categorised as a Financial tool in the Polymarket MCP Server MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on kelly_size? +

Register the Polymarket MCP Server MCP server in PolicyLayer and add a rule for kelly_size: 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 Polymarket MCP Server. Nothing to install.

What risk level is kelly_size? +

kelly_size 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 kelly_size? +

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

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

kelly_size is provided by the Polymarket MCP Server MCP server (miles0sage/polymarket-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.