send_correction_letter

THE RISK

Medium Risk

Why send_correction_letter needs a policy

The tool creates a new correction document tied to an existing authorized fiscal record. While it does not delete or directly modify the original NFe, it generates a supplementary legal instrument that changes the fiscal record's effective status. This is reversible in principle (further corrections can follow), but it has regulatory and financial audit implications.

From the tool's definition 'Send a correction letter' — creates or modifies (via correction) an authorized NFe (Nota Fiscal Eletrônica). A CCe is a legally binding correction document issued against an existing fiscal document.

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

POLICY

How to control send_correction_letter

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 send_correction_letter:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "send_correction_letter": {
      "limits": [
        {
          "counter": "send_correction_letter_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

send_correction_letter stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

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

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

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All 1300 Mcp Ap2 tools →

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about send_correction_letter

What does the send_correction_letter tool do? +

Send a correction letter (Carta de Correcao / CCe) for an authorized NFe. It is categorised as a Write tool in the Mcp Ap2 MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on send_correction_letter? +

Register the Mcp Ap2 MCP server in PolicyLayer and add a rule for send_correction_letter: 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 send_correction_letter? +

send_correction_letter is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit send_correction_letter? +

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

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

send_correction_letter 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.

Start from Mcp Ap2, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →