card_lock_update · Starling Bank MCP: Risk & Policy

WHAT IT DOES

What card_lock_update does on Starling Bank

AI agents invoke card_lock_update to trigger actions in Starling Bank. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why card_lock_update needs a policy

This tool controls the lock/unlock state of a bank card, which is an external operation with significant security implications. It's not purely destructive (it's reversible — you can re-lock or unlock), and it doesn't directly move money, but it enables or restricts financial transactions.

From the tool's definition 'Enable or disable (lock/unlock) a card' — triggers an external state change on a financial card

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

card_lock_update Rate-limited

card_lock_update stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "card_lock_update": {
      "limits": [
        {
          "counter": "card_lock_update_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Starling Bank, so you can run agents against it safely.

FAQ

Questions about card_lock_update

What does the card_lock_update tool do? +

Enable or disable (lock/unlock) a card. It is categorised as a Execute tool in the Starling Bank MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on card_lock_update? +

Register the Starling Bank MCP server in PolicyLayer and add a rule for card_lock_update: 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 Starling Bank. Nothing to install.

What risk level is card_lock_update? +

card_lock_update is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit card_lock_update? +

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

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

card_lock_update is provided by the Starling Bank MCP server (starling-bank-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.