List all transit agencies served by this OneBusAway instance. Returns agency IDs, names, contact info, timezone, and geographic coverage center. Agency IDs are needed for onebusaway_list_routes_for_agency and onebusaway_get_vehicles.
Part of the Onebusaway Mcp Server server.
Free to start. No card required.
AI agents call onebusaway_list_agencies to retrieve information from Onebusaway Mcp Server 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 onebusaway_list_agencies 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": {
"onebusaway_list_agencies": {}
}
}See the full Onebusaway Mcp Server policy for all 15 tools.
These attack patterns abuse exactly the kind of access onebusaway_list_agencies 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.
List all transit agencies served by this OneBusAway instance. Returns agency IDs, names, contact info, timezone, and geographic coverage center. Agency IDs are needed for onebusaway_list_routes_for_agency and onebusaway_get_vehicles.. It is categorised as a Read tool in the Onebusaway Mcp Server MCP Server, which means it retrieves data without modifying state.
Register the Onebusaway Mcp Server MCP server in PolicyLayer and add a rule for onebusaway_list_agencies: 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 Onebusaway Mcp Server. Nothing to install.
onebusaway_list_agencies 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 onebusaway_list_agencies 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 onebusaway_list_agencies. 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.
onebusaway_list_agencies is provided by the Onebusaway Mcp Server MCP server (@cyanheads/onebusaway-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 15 Onebusaway Mcp Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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