myob_bill_prepare_update · MYOB Codex MCP: Risk & Policy

WHAT IT DOES

What myob_bill_prepare_update does on MYOB Codex MCP

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

WHY IT NEEDS A POLICY

Why myob_bill_prepare_update needs a policy

This tool creates or modifies purchase bill data (a Write action), affecting financial records in an accounting system. While the modification requires explicit approval before commit, the tool itself prepares the mutation.

From the tool's definition Tool name and description indicate it 'Prepare[s] update of a purchase bill' and 'Requires approval before commit,' showing it modifies financial records (bills) reversibly prior to final approval.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

myob_bill_prepare_update Rate-limited

myob_bill_prepare_update 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": {
    "myob_bill_prepare_update": {
      "limits": [
        {
          "counter": "myob_bill_prepare_update_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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

FAQ

Questions about myob_bill_prepare_update

What does the myob_bill_prepare_update tool do? +

Prepare update of a purchase bill. Requires approval before commit. It is categorised as a Write tool in the MYOB Codex 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 myob_bill_prepare_update? +

Register the MYOB Codex MCP server in PolicyLayer and add a rule for myob_bill_prepare_update: 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 MYOB Codex MCP. Nothing to install.

What risk level is myob_bill_prepare_update? +

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

Can I rate-limit myob_bill_prepare_update? +

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

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

myob_bill_prepare_update is provided by the MYOB Codex MCP server (jaeko44/myob-codex-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.