create_supplier_invoice · Fortnox MCP: Risk & Policy

WHAT IT DOES

What create_supplier_invoice does on Fortnox

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

WHY IT NEEDS A POLICY

Why create_supplier_invoice needs a policy

This tool creates a new supplier invoice, which writes data to the accounting system and establishes a financial obligation. While it modifies records reversibly (invoices can be deleted or corrected), it does not move money directly (making it not Financial) nor is it destructive. The high severity reflects that misuse could create fraudulent expense records, incorrectly allocate costs, or inflate liabilities.

From the tool's definition Tool name 'create_supplier_invoice' and description 'Record a new supplier invoice (expense/bill)' indicate the tool creates a new accounting entry that modifies financial records.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_supplier_invoice Rate-limited

create_supplier_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": {
    "create_supplier_invoice": {
      "limits": [
        {
          "counter": "create_supplier_invoice_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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 Fortnox, so you can run agents against it safely.

FAQ

Questions about create_supplier_invoice

What does the create_supplier_invoice tool do? +

Record a new supplier invoice (expense/bill). It is categorised as a Write tool in the Fortnox MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_supplier_invoice? +

Register the Fortnox MCP server in PolicyLayer and add a rule for create_supplier_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 Fortnox. Nothing to install.

What risk level is create_supplier_invoice? +

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

Can I rate-limit create_supplier_invoice? +

Yes. Add a rate_limit block to the create_supplier_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 create_supplier_invoice completely? +

Set action: deny in the PolicyLayer policy for create_supplier_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 create_supplier_invoice? +

create_supplier_invoice is provided by the Fortnox MCP server (proviscale/fortnox-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.