cancel_nfe

THE RISK

Critical Risk

Why cancel_nfe needs a policy

Canceling an authorized NFe (Nota Fiscal Eletrônica) is a destructive operation that irreversibly voids a financial/tax document. While it has a time window restriction (24h), the cancellation itself is irreversible and constitutes destruction of a financial record. This exceeds Write (which is reversible modification) and qualifies as Destructive.

From the tool's definition Tool name 'cancel_nfe' combined with description 'Cancel an authorized NFe (within 24h of emission)' indicates irreversible cancellation of a financial document (NFe is a Brazilian electronic invoice). The action cannot be undone and affects financial records.

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

POLICY

How to control cancel_nfe

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 cancel_nfe:

policy.json

{
  "version": "1",
  "default": "deny",
  "hide": [
    "cancel_nfe"
  ]
}

cancel_nfe disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

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.

RESTRICT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Mcp Ap2 tools

Financial authorize_transaction Authorize a transaction (reserve funds without capturing) via Braintree GraphQL authorizeP Financial block_card Block a card temporarily (reversible). Use for lost-card or fraud-suspected flows. Card st Financial cancel_bill Cancel a pending bill Financial cancel_collection Cancel a scheduled collection request Financial cancel_credit Cancel an authorized-but-uncaptured credit payment. Financial cancel_debit Cancel a debit-card payment by Getnet payment_id. Financial cancel_invoice Cancel/void an authorized invoice (FECancel — limited to certain types/conditions) Financial cancel_order Cancel an order, optionally restocking and refunding

All 1300 Mcp Ap2 tools →

Destructive tools on other servers

Android Forensics ADB MCP Server create_full_backup 0xarchive web3_revoke_key Frida Game Hacking MCP clear_scan cPanel MCP Server clear_spam_box

Go deeper

Critical-risk tools in Mcp Ap2 → Every critical-risk tool this server exposes, in one view.
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.
Blast radius → How much damage one compromised or confused agent can do — and how to bound it.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about cancel_nfe

What does the cancel_nfe tool do? +

Cancel an authorized NFe (within 24h of emission). It is categorised as a Destructive tool in the Mcp Ap2 MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on cancel_nfe? +

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

cancel_nfe is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit cancel_nfe? +

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

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

cancel_nfe 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 →