update_expense · Smokeball MCP: Risk & Policy

WHAT IT DOES

What update_expense does on Smokeball

AI agents use update_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 update_expense needs a policy

This tool modifies expense records in a law firm practice management system, which is reversible. While it affects financial tracking, it does not move money or commit financial obligations itself—it updates metadata about expenses. The Write category is appropriate as it creates or modifies data reversibly.

From the tool's definition Tool name 'update_expense' and description 'Update an expense entry' directly indicates modification of existing data. The parameter 'billable' can be set to 'true' or 'false', allowing the tool to change expense billing status.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_expense Rate-limited

update_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": {
    "update_expense": {
      "limits": [
        {
          "counter": "update_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 update_expense

What does the update_expense tool do? +

Update an expense entry. billable: 'true' or 'false' to set; leave empty to skip. 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 update_expense? +

Register the Smokeball MCP server in PolicyLayer and add a rule for update_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 update_expense? +

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

Can I rate-limit update_expense? +

Yes. Add a rate_limit block to the update_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 update_expense completely? +

Set action: deny in the PolicyLayer policy for update_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 update_expense? +

update_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.