Critical Risk →

update_pix_charge

Update (PATCH) a Pix immediate charge (cob) — e.g. change amount before payment, adjust expiration, or mark as REMOVIDA_PELO_USUARIO_RECEBEDOR.

How to control update_pix_charge ↓

What update_pix_charge does on Mcp Ap2

AI agents use update_pix_charge to commit financial operations through Mcp Ap2 — usually the final step of a payment, billing, or trading workflow. A call moves real money.

Critical Risk

Why update_pix_charge needs a policy

This tool modifies existing financial charges/payment requests in an active payment system. Changing the amount or expiration of a charge before payment constitutes a financial operation that moves or commits money. While the change occurs before final payment, the tool's core function is manipulating monetary transaction parameters.

From the tool's definition Tool name 'update_pix_charge' and description explicitly mentions updating a Pix charge (cob — comprovante de oferta de breve duração, a Brazilian instant payment mechanism).

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

How to control update_pix_charge

PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Ap2, and nothing reaches the server without passing your rules. This is the rule we recommend for update_pix_charge:

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

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

  1. Create a free account and register Mcp Ap2 — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
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Related tools and policies

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Questions about update_pix_charge

What does the update_pix_charge tool do? +

Update (PATCH) a Pix immediate charge (cob) — e.g. change amount before payment, adjust expiration, or mark as REMOVIDA_PELO_USUARIO_RECEBEDOR. It is categorised as a Financial tool in the Mcp Ap2 MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on update_pix_charge? +

Register the Mcp Ap2 MCP server in PolicyLayer and add a rule for update_pix_charge: 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 Mcp Ap2. Nothing to install.

What risk level is update_pix_charge? +

update_pix_charge 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 update_pix_charge? +

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

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

update_pix_charge is provided by the Mcp Ap2 MCP server (@codespar/mcp-ap2). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Mcp Ap2 tool call.

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