Current service status for London transport lines. Pass either a comma-separated list of modes (e.g. "tube,dlr") OR a specific lineId (e.g. "victoria", "central"). Returns each line with lineStatuses + statusSeverityDescription (e.g. "Good Service", "Minor Delays").
Part of the Tfl server.
Free to start. No card required.
AI agents call line_status to retrieve information from Tfl 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 line_status 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": {
"line_status": {}
}
}See the full Tfl policy for all 26 tools.
These attack patterns abuse exactly the kind of access line_status 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.
Current service status for London transport lines. Pass either a comma-separated list of modes (e.g. "tube,dlr") OR a specific lineId (e.g. "victoria", "central"). Returns each line with lineStatuses + statusSeverityDescription (e.g. "Good Service", "Minor Delays").. It is categorised as a Read tool in the Tfl MCP Server, which means it retrieves data without modifying state.
Register the Tfl MCP server in PolicyLayer and add a rule for line_status: 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 Tfl. Nothing to install.
line_status 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 line_status 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 line_status. 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.
line_status is provided by the Tfl MCP server (https://gateway.pipeworx.io/tfl/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 26 Tfl tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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