ksef_prepare_invoice · KSeF MCP: Risk & Policy

WHAT IT DOES

What ksef_prepare_invoice does on KSeF MCP

AI agents use ksef_prepare_invoice to create or update resources in KSeF MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your KSeF MCP environment.

WHY IT NEEDS A POLICY

Why ksef_prepare_invoice needs a policy

The tool creates/builds an invoice XML document and validates it, but explicitly does NOT send it. This is a reversible write/creation action with no submission side effect. The safety gate ('refuses until TEST readiness passes') confirms no external submission occurs. Severity is medium because invoice data is sensitive financial information, but since nothing is transmitted, blast radius is limited.

From the tool's definition Build and validate invoice XML without sending; refuses until TEST readiness passes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ksef_prepare_invoice Rate-limited

ksef_prepare_invoice 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.

View as policy code

policy.json

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

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about ksef_prepare_invoice

What does the ksef_prepare_invoice tool do? +

Build and validate invoice XML without sending; refuses until TEST readiness passes. It is categorised as a Write tool in the KSeF MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on ksef_prepare_invoice? +

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

What risk level is ksef_prepare_invoice? +

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

Can I rate-limit ksef_prepare_invoice? +

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

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

ksef_prepare_invoice is provided by the KSeF MCP server (olegtyshcneko/ksef-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.