Create a bill (AP / money owed to a vendor). VendorRef and at least one Line (AccountBasedExpenseLineDetail or ItemBasedExpenseLineDetail) are required.
AI agents use create_bill to create or update resources in Mcp Afip — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mcp Afip environment.
While this tool involves financial records (accounts payable/bills), it creates or records a financial obligation rather than executing a payment or moving money. The tool writes/creates a structured financial record in the accounting system. This is reversible (bills can be amended or voided), distinguishing it from Destructive or Financial categories.
From the tool's definition Tool name 'create_bill' and description states it 'Create[s] a bill (AP / money owed to a vendor)' with required fields for vendor reference and expense line details. This is a financial data creation operation.
Documented attack patterns abuse exactly the kind of access create_bill gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Afip, and nothing reaches the server without passing your rules. This is the rule we recommend for create_bill:
{
"version": "1",
"default": "deny",
"tools": {
"create_bill": {
"limits": [
{
"counter": "create_bill_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_bill 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.
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Create a bill (AP / money owed to a vendor). VendorRef and at least one Line (AccountBasedExpenseLineDetail or ItemBasedExpenseLineDetail) are required. It is categorised as a Write tool in the Mcp Afip MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Mcp Afip MCP server in PolicyLayer and add a rule for create_bill: 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 Afip. Nothing to install.
create_bill is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the create_bill 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.
Set action: deny in the PolicyLayer policy for create_bill. 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.
create_bill is provided by the Mcp Afip MCP server (codespar/mcp-dev-latam). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Mcp Afip, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
1300 Mcp Afip tools catalogued and risk-classified — across an index of 43,000+ MCP servers.