PLN exchange rate for one currency over time. Specify the table (A/B for mid-rate, C for bid/ask) and a 3-letter ISO 4217 code (e.g. USD, EUR, GBP, CHF, JPY). Defaults to the latest rate; optionally pass a single date, last_n recent points, or a start_date/end_date window (max ~93 days, working d...
Risk signalsAccepts freeform code/query input (code)
Part of the Nbp Pl server.
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AI agents call currency_rate to retrieve information from Nbp Pl 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 currency_rate 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": {
"currency_rate": {}
}
}See the full Nbp Pl policy for all 23 tools.
These attack patterns abuse exactly the kind of access currency_rate 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.
PLN exchange rate for one currency over time. Specify the table (A/B for mid-rate, C for bid/ask) and a 3-letter ISO 4217 code (e.g. USD, EUR, GBP, CHF, JPY). Defaults to the latest rate; optionally pass a single date, last_n recent points, or a start_date/end_date window (max ~93 days, working days only). Use this for one currency; use exchange_rate_table for the whole list.. It is categorised as a Read tool in the Nbp Pl MCP Server, which means it retrieves data without modifying state.
Register the Nbp Pl MCP server in PolicyLayer and add a rule for currency_rate: 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 Nbp Pl. Nothing to install.
currency_rate 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 currency_rate 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 currency_rate. 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.
currency_rate is provided by the Nbp Pl MCP server (https://gateway.pipeworx.io/nbp-pl/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 23 Nbp Pl tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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