patch_expense · Smokeball MCP: Risk & Policy

WHAT IT DOES

What patch_expense does on Smokeball

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

WHY IT NEEDS A POLICY

Why patch_expense needs a policy

This tool modifies financial-related data (expense billing status) in a law firm practice management system. While it affects billing records, the operation itself is reversible—the state can be toggled back. This makes it Write rather than Financial (which would apply to tools that move money or create obligations).

From the tool's definition Tool name 'patch_expense' and description 'Toggle an expense entry's billable or billed state (PATCH)' indicates modification of an existing expense record.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

patch_expense Rate-limited

patch_expense 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": {
    "patch_expense": {
      "limits": [
        {
          "counter": "patch_expense_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 Smokeball, so you can run agents against it safely.

FAQ

Questions about patch_expense

What does the patch_expense tool do? +

Toggle an expense entry's billable or billed state (PATCH). Use 'true' or 'false'. It is categorised as a Write tool in the Smokeball MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on patch_expense? +

Register the Smokeball MCP server in PolicyLayer and add a rule for patch_expense: 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 Smokeball. Nothing to install.

What risk level is patch_expense? +

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

Can I rate-limit patch_expense? +

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

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

patch_expense is provided by the Smokeball MCP server (rosenadvertising/smokeball-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.