add_transaction · Actual MCP: Risk & Policy

WHAT IT DOES

What add_transaction does on Actual

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

WHY IT NEEDS A POLICY

Why add_transaction needs a policy

This tool creates a new transaction record in Actual Budget. While it doesn't move real money, it modifies financial records in a budgeting system. This is reversible in principle (the transaction could be deleted), so it falls under Write rather than Financial (no actual money movement) or Destructive.

From the tool's definition 'Adds a new transaction to an account' — creates new financial transaction data in the budget system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_transaction Rate-limited

add_transaction 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": {
    "add_transaction": {
      "limits": [
        {
          "counter": "add_transaction_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 Actual, so you can run agents against it safely.

FAQ

Questions about add_transaction

What does the add_transaction tool do? +

Adds a new transaction to an account. It is categorised as a Write tool in the Actual MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_transaction? +

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

What risk level is add_transaction? +

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

Can I rate-limit add_transaction? +

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

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

add_transaction is provided by the Actual MCP server (slushpupie/actual-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.