expense.correct · Mcp Finance MCP: Risk & Policy

WHAT IT DOES

What expense.correct does on Mcp Finance

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

WHY IT NEEDS A POLICY

Why expense.correct needs a policy

This tool modifies existing expense data (category correction) and creates/updates heuristic rules (ClassificationRule, Merchant.defaultCategoryId). Both are reversible write operations — the expense still exists, only its category is changed, and new rules are created rather than deleting anything. No money movement is involved, and no irreversible destruction occurs.

From the tool's definition 'Actualiza la categoría (categoryId) de un Expense ya persistido' — updates/modifies an already-persisted expense record; also 'aprende una heurística' meaning it writes classification rules or merchant defaults

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

expense.correct Rate-limited

expense.correct 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": {
    "expense.correct": {
      "limits": [
        {
          "counter": "expense.correct_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 Mcp Finance, so you can run agents against it safely.

FAQ

Questions about expense.correct

What does the expense.correct tool do? +

Actualiza la categoría (categoryId) de un Expense ya persistido y aprende una heurística (Merchant.defaultCategoryId o ClassificationRule). It is categorised as a Write tool in the Mcp Finance MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on expense.correct? +

Register the Mcp Finance MCP server in PolicyLayer and add a rule for expense.correct: 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 Finance. Nothing to install.

What risk level is expense.correct? +

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

Can I rate-limit expense.correct? +

Yes. Add a rate_limit block to the expense.correct 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 expense.correct completely? +

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

expense.correct is provided by the Mcp Finance MCP server (toothlesstarantula/mcp-finance). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.