CZEONIA — the Czech Overnight Index Average (the reference rate for actual overnight CZK interbank deposits) for a given day. Returns validFor, the overnight rate (percent) and traded volume in CZK millions. Omit date for the latest. Verified live.
Part of the Cnb Cz server.
Free to start. No card required.
AI agents call czeonia to retrieve information from Cnb Cz 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 czeonia 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": {
"czeonia": {}
}
}See the full Cnb Cz policy for all 25 tools.
These attack patterns abuse exactly the kind of access czeonia 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.
CZEONIA — the Czech Overnight Index Average (the reference rate for actual overnight CZK interbank deposits) for a given day. Returns validFor, the overnight rate (percent) and traded volume in CZK millions. Omit date for the latest. Verified live.. It is categorised as a Read tool in the Cnb Cz MCP Server, which means it retrieves data without modifying state.
Register the Cnb Cz MCP server in PolicyLayer and add a rule for czeonia: 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 Cnb Cz. Nothing to install.
czeonia 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 czeonia 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 czeonia. 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.
czeonia is provided by the Cnb Cz MCP server (https://gateway.pipeworx.io/cnb-cz/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 25 Cnb Cz tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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