retrieve_balance

THE RISK

Low Risk

Why retrieve_balance needs a policy

This tool retrieves financial data (wallet balance across currencies) but does not move money, create obligations, or modify state. It is a read-only query of account information. While the server handles payments and financial operations (AP2 is Google's Agent-to-Agent Payment Protocol), this specific tool only fetches current balance information without any write or transactional capability.

From the tool's definition Tool name is 'retrieve_balance' and description states it 'Retrieve[s] the current wallet balance' — a query operation with no side effects.

Risk signalsBulk/mass operation — affects multiple targets

Documented attack patterns abuse exactly the kind of access retrieve_balance gives an agent:

POLICY

How to control retrieve_balance

PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Ap2, and nothing reaches the server without passing your rules. This is the rule we recommend for retrieve_balance:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "retrieve_balance": {}
  }
}

retrieve_balance is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Mcp Ap2 — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Mcp Ap2 tools

Financial authorize_transaction Authorize a transaction (reserve funds without capturing) via Braintree GraphQL authorizeP Financial block_card Block a card temporarily (reversible). Use for lost-card or fraud-suspected flows. Card st Financial cancel_bill Cancel a pending bill Financial cancel_collection Cancel a scheduled collection request Financial cancel_credit Cancel an authorized-but-uncaptured credit payment. Financial cancel_debit Cancel a debit-card payment by Getnet payment_id. Financial cancel_invoice Cancel/void an authorized invoice (FECancel — limited to certain types/conditions) Financial cancel_order Cancel an order, optionally restocking and refunding

All 1300 Mcp Ap2 tools →

Read tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about retrieve_balance

What does the retrieve_balance tool do? +

Retrieve the current wallet balance for every currency the account holds. It is categorised as a Read tool in the Mcp Ap2 MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on retrieve_balance? +

Register the Mcp Ap2 MCP server in PolicyLayer and add a rule for retrieve_balance: 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 Mcp Ap2. Nothing to install.

What risk level is retrieve_balance? +

retrieve_balance is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit retrieve_balance? +

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

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

retrieve_balance is provided by the Mcp Ap2 MCP server (@codespar/mcp-ap2). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Mcp Ap2 tool call.

Start from Mcp Ap2, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →