NBP accounting price of gold (cena złota): PLN per 1 gram of pure gold (1000 fineness). Defaults to the latest published price; optionally pass a single date, last_n recent points, or a start_date/end_date window (max ~93 days, working days only). Weekends/Polish holidays have no data (404).
Part of the Nbp Pl server.
Free to start. No card required.
AI agents call gold_price 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 gold_price 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": {
"gold_price": {}
}
}See the full Nbp Pl policy for all 23 tools.
These attack patterns abuse exactly the kind of access gold_price 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.
NBP accounting price of gold (cena złota): PLN per 1 gram of pure gold (1000 fineness). Defaults to the latest published price; optionally pass a single date, last_n recent points, or a start_date/end_date window (max ~93 days, working days only). Weekends/Polish holidays have no data (404).. 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 gold_price: 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.
gold_price 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 gold_price 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 gold_price. 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.
gold_price 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.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.