approve_moolah_vault · Justlend MCP: Risk & Policy

WHAT IT DOES

What approve_moolah_vault does on Justlend

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

WHY IT NEEDS A POLICY

Why approve_moolah_vault needs a policy

Token approval is a Write operation—it modifies the allowance state of a TRC20 token contract, permitting the vault to spend tokens on behalf of the user. This is reversible (allowances can be reset to zero), but carries high severity because a compromised agent could approve unlimited spending, leading to unauthorized token transfers. The context of a lending/borrowing protocol amplifies financial risk.

From the tool's definition Tool name 'approve_moolah_vault' and description 'Approve TRC20 token spending for a Moolah vault before depositing' indicates token approval operations. This is a reversible modification of smart contract allowance state.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

approve_moolah_vault Rate-limited

approve_moolah_vault 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": {
    "approve_moolah_vault": {
      "limits": [
        {
          "counter": "approve_moolah_vault_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 Justlend, so you can run agents against it safely.

FAQ

Questions about approve_moolah_vault

What does the approve_moolah_vault tool do? +

Approve TRC20 token spending for a Moolah vault before depositing. It is categorised as a Write tool in the Justlend MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on approve_moolah_vault? +

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

What risk level is approve_moolah_vault? +

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

Can I rate-limit approve_moolah_vault? +

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

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

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