wave_update_invoice · Waveapps MCP: Risk & Policy

WHAT IT DOES

What wave_update_invoice does on Waveapps

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

WHY IT NEEDS A POLICY

Why wave_update_invoice needs a policy

This tool creates or modifies invoice data reversibly—a core Write category action. It is not Destructive (no deletion/irreversible action), not Execute (no code execution), and not Financial (does not move money or commit new obligations; it updates existing invoice state).

From the tool's definition Tool name 'wave_update_invoice' and description 'Patches an invoice via REST' indicates modification of existing financial documents. The verb 'patches' (HTTP PATCH) means partial update, which is reversible and modifies data without deletion.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

wave_update_invoice Rate-limited

wave_update_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": {
    "wave_update_invoice": {
      "limits": [
        {
          "counter": "wave_update_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 Waveapps, so you can run agents against it safely.

FAQ

Questions about wave_update_invoice

What does the wave_update_invoice tool do? +

Patches an invoice via REST. It is categorised as a Write tool in the Waveapps MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on wave_update_invoice? +

Register the Waveapps MCP server in PolicyLayer and add a rule for wave_update_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 Waveapps. Nothing to install.

What risk level is wave_update_invoice? +

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

Can I rate-limit wave_update_invoice? +

Yes. Add a rate_limit block to the wave_update_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 wave_update_invoice completely? +

Set action: deny in the PolicyLayer policy for wave_update_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 wave_update_invoice? +

wave_update_invoice is provided by the Waveapps MCP server (lunaparker/waveapps-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.