AI agents call get_live_arrivals to retrieve information from Mcp National Rail without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and retrieves real-time train arrival data from the National Rail API. It performs a read-only operation that returns information without modifying, executing external commands, or affecting any data. The sibling tools (get_arrivals_by_date, get_departures_by_date, get_live_departures) are all informational queries, consistent with a Read category classification.
From the tool's definition Tool name 'get_live_arrivals' and description 'Get live arrival information for a station' indicate a retrieval operation with no side effects.
Documented attack patterns abuse exactly the kind of access get_live_arrivals gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp National Rail, and nothing reaches the server without passing your rules. This is the rule we recommend for get_live_arrivals:
{
"version": "1",
"default": "deny",
"tools": {
"get_live_arrivals": {}
}
}get_live_arrivals is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Get live arrival information for a station. It is categorised as a Read tool in the Mcp National Rail MCP Server, which means it retrieves data without modifying state.
Register the Mcp National Rail MCP server in PolicyLayer and add a rule for get_live_arrivals: 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 Mcp National Rail. Nothing to install.
get_live_arrivals 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 get_live_arrivals 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 get_live_arrivals. 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.
get_live_arrivals is provided by the Mcp National Rail MCP server (lucygoodchild/mcp-national-rail). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Mcp National Rail, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
4 Mcp National Rail tools catalogued and risk-classified — across an index of 43,000+ MCP servers.