List cities supported by the realtime bus data service. Args: - hot_only (boolean, default true): return only the upstream
AI agents call bus_list_cities to retrieve information from Chelaile without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a straightforward read operation—listing supported cities from a public transit data service. It retrieves information without creating, modifying, or deleting any data. The severity is low because the blast radius of listing available cities is minimal; there is no sensitive data exposure, no financial impact, and no operational risk even if called inappropriately by an agent.
From the tool's definition Tool name 'bus_list_cities' and description 'List cities supported by the realtime bus data service' indicate a query operation that retrieves and enumerates available cities. The sole argument 'hot_only' filters results rather than modifying state.
Documented attack patterns abuse exactly the kind of access bus_list_cities gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Chelaile, and nothing reaches the server without passing your rules. This is the rule we recommend for bus_list_cities:
{
"version": "1",
"default": "deny",
"tools": {
"bus_list_cities": {}
}
}bus_list_cities is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List cities supported by the realtime bus data service. Args: - hot_only (boolean, default true): return only the upstream. It is categorised as a Read tool in the Chelaile MCP Server, which means it retrieves data without modifying state.
Register the Chelaile MCP server in PolicyLayer and add a rule for bus_list_cities: 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 Chelaile. Nothing to install.
bus_list_cities 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 bus_list_cities 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 bus_list_cities. 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.
bus_list_cities is provided by the Chelaile MCP server (peanutsplash/chelaile-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Chelaile, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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15 Chelaile tools catalogued and risk-classified — across an index of 43,000+ MCP servers.