Returns accounts for a bank connection: BANK (checking/savings) and CREDIT (credit card) with balance, number, type, subtype, bankData, and creditData. Also returns bank (the brand/connector name like 'Nubank Empresas' — same shown in the dashboard UI) and connector_id. Note: each account's name ...
Risk signalsAdmin/system-level operation
Part of the Banco MCP server.
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AI agents call openfinance_list_accounts to retrieve information from Banco MCP without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though openfinance_list_accounts only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"openfinance_list_accounts": {}
}
}See the full Banco MCP policy for all 22 tools.
These attack patterns abuse exactly the kind of access openfinance_list_accounts gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Returns accounts for a bank connection: BANK (checking/savings) and CREDIT (credit card) with balance, number, type, subtype, bankData, and creditData. Also returns bank (the brand/connector name like 'Nubank Empresas' — same shown in the dashboard UI) and connector_id. Note: each account's name is the legal entity that issues the account (e.g. 'Nu Pagamentos S.A. - Instituição de Pagamento'), which is not the same as the brand — when referring to the bank in user-facing text, use bank. OMIT item to list accounts across ALL linked banks at once — the response aggregates every connection's accounts into results, each row tagged with its own bank/connector_id/item_id (use this when the user asks for 'my accounts/cards' without naming a bank). Pass item to target a single bank (response carries bank/connector_id/item_id at the root).. It is categorised as a Read tool in the Banco MCP MCP Server, which means it retrieves data without modifying state.
Register the Banco MCP server in PolicyLayer and add a rule for openfinance_list_accounts: 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 Banco MCP. Nothing to install.
openfinance_list_accounts is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the openfinance_list_accounts 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.
Set action: deny in the PolicyLayer policy for openfinance_list_accounts. 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.
openfinance_list_accounts is provided by the Banco MCP server (https://api.mcp.ai/banco). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 22 Banco MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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