siigo_update_purchase · Siigo MCP Server MCP: Risk & Policy

WHAT IT DOES

What siigo_update_purchase does on Siigo MCP Server

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

WHY IT NEEDS A POLICY

Why siigo_update_purchase needs a policy

This tool modifies financial records (purchase invoices) in a live accounting system. While categorized as Write rather than Destructive because updates are typically reversible, the high severity reflects the critical nature of purchase data in financial accounting.

From the tool's definition Tool name is siigo_update_purchase and description states 'Update an existing purchase invoice'. The verb 'update' indicates modification of existing data in the accounting system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

siigo_update_purchase Rate-limited

siigo_update_purchase 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": {
    "siigo_update_purchase": {
      "limits": [
        {
          "counter": "siigo_update_purchase_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about siigo_update_purchase

What does the siigo_update_purchase tool do? +

Update an existing purchase invoice. It is categorised as a Write tool in the Siigo MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on siigo_update_purchase? +

Register the Siigo MCP Server MCP server in PolicyLayer and add a rule for siigo_update_purchase: 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.

What risk level is siigo_update_purchase? +

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

Can I rate-limit siigo_update_purchase? +

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

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

siigo_update_purchase 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.