add_credit · Expense Tracker MCP Server MCP: Risk & Policy

WHAT IT DOES

What add_credit does on Expense Tracker MCP Server

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

WHY IT NEEDS A POLICY

Why add_credit needs a policy

While this tool modifies credit account information (which has financial implications), it does not execute actual financial transactions, move real money, or commit external financial obligations. It updates the local database record of credits, which is reversible (credits can be edited or deleted via sibling tools). This places it in the Write category rather than Financial.

From the tool's definition Tool description states 'Add credit to the user's account', which creates or modifies account data reversibly. The action is a write operation that updates financial account state in the local database.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_credit Rate-limited

add_credit 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_credit": {
      "limits": [
        {
          "counter": "add_credit_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 Expense Tracker MCP Server, so you can run agents against it safely.

FAQ

Questions about add_credit

What does the add_credit tool do? +

Add credit to the user's account. By default updates 'default' user. It is categorised as a Write tool in the Expense Tracker 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 add_credit? +

Register the Expense Tracker MCP Server MCP server in PolicyLayer and add a rule for add_credit: 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 Expense Tracker MCP Server. Nothing to install.

What risk level is add_credit? +

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

Can I rate-limit add_credit? +

Yes. Add a rate_limit block to the add_credit 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_credit completely? +

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

add_credit is provided by the Expense Tracker MCP Server MCP server (pk-sangameswar/mcp-expense-tracker). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.