Annul (void) a sales invoice
AI agents call siigo_annul_invoice to permanently remove resources in Siigo MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Annulling or voiding an invoice is an irreversible operation in accounting systems. Once a sales invoice is annulled, it cannot be restored to its original state; this is a permanent cancellation. This qualifies as Destructive. The blast radius is high because it affects financial records and customer billing.
From the tool's definition Annul (void) a sales invoice — voiding/annulling an invoice is an irreversible accounting action that cancels the document permanently
Attacks that exploit this kind of access
Annul (void) a sales invoice. It is categorised as a Destructive tool in the Siigo MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Siigo MCP Server MCP server in PolicyLayer and add a rule for siigo_annul_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 Siigo MCP Server. Nothing to install.
siigo_annul_invoice is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the siigo_annul_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.
Set action: deny in the PolicyLayer policy for siigo_annul_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.
siigo_annul_invoice is provided by the Siigo MCP Server MCP server (jdlar1/siigo-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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