set_active_wallet · Justlend MCP: Risk & Policy

WHAT IT DOES

What set_active_wallet does on Justlend

AI agents use set_active_wallet 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 set_active_wallet needs a policy

This tool changes application state (the active/selected wallet) in a reversible manner. It does not permanently delete data (not Destructive), does not move funds directly (not Financial), and does not execute arbitrary code (not Execute).

From the tool's definition Tool description states it 'Set[s] the active wallet by wallet ID', which modifies the state of which wallet is currently active. This is a configuration change that affects subsequent operations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_active_wallet Rate-limited

set_active_wallet 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": {
    "set_active_wallet": {
      "limits": [
        {
          "counter": "set_active_wallet_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 set_active_wallet

What does the set_active_wallet tool do? +

Set the active wallet by wallet ID. Use list_wallets to see available wallet IDs. 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 set_active_wallet? +

Register the Justlend MCP server in PolicyLayer and add a rule for set_active_wallet: 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 set_active_wallet? +

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

Can I rate-limit set_active_wallet? +

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

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

set_active_wallet 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.