tfl.transit.arrivals

SERVERApibase SOURCEapibase-mcp-client

Medium RISK CLASS

Category Write

Parameters 42 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-whiteknightonhorse-apibase/tfl.transit.arrivals.md

WHAT IT DOES

What tfl.transit.arrivals does on Apibase

AI agents use tfl.transit.arrivals to create or update resources in Apibase, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Apibase environment.

Parameter	Type	Required	Description
`limit`	integer	—	Maximum number of arrival predictions to return, sorted by soonest first (1–50). Defaults to 20.
`line_id`	string	Yes	TfL line ID (e.g. central, bakerloo, victoria, northern, jubilee, elizabeth, overground, dlr, piccadilly). Use lowercase, hyphens for multi-word lines (e.g. eli
`stop_id`	string	Yes	NAPTAN stop point ID for the station (e.g. 940GZZLUHPK for Holland Park, 940GZZLUKSX for Kings Cross St. Pancras). Format: 940GZZLU + station code for tube stop
`direction`	string	—	Filter arrivals by direction of travel (inbound, outbound, or all). Defaults to all directions.

Parameters from the server's own tool schema.

RISK

Why tfl.transit.arrivals is rated Medium

An AI agent can call tfl.transit.arrivals faster than any human can review: one bad instruction and it creates or modifies resources in Apibase by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs tfl.transit.arrivals safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Apibase, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For tfl.transit.arrivals, this is the rule to start with:

tfl.transit.arrivals Rate-limited

tfl.transit.arrivals stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "tfl.transit.arrivals": {
      "limits": [
        {
          "counter": "tfl.transit.arrivals_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Apibase, apply this rule, and every tfl.transit.arrivals call is checked against it from then on.

FAQ

Questions about tfl.transit.arrivals

What does the tfl.transit.arrivals tool do? +

Get live arrival predictions for a specific TfL line at a London stop or station. Returns upcoming trains sorted by soonest arrival, with destination, platform, direction, and minutes until arrival. Requires a line_id (e.g. central, bakerloo, jubilee, victoria, elizabeth, dlr, overground) and a NAPTAN stop_id (e.g. 940GZZLUHPK for Holland Park, 940GZZLUKSX for Kings Cross). Arrival predictions update every 30 seconds from the TfL real-time feed. Use direction=inbound/outbound to filter by travel direction. Source: TfL Unified API — api.tfl.gov.uk. No auth required, TfL Open Data CC-BY. It is categorised as a Write tool in the Apibase MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does tfl.transit.arrivals accept? +

tfl.transit.arrivals accepts 4 parameters: limit, line_id, stop_id, direction. Required: line_id, stop_id. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on tfl.transit.arrivals? +

Register the Apibase MCP server in PolicyLayer and add a rule for tfl.transit.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 Apibase. Nothing to install.

What risk level is tfl.transit.arrivals? +

tfl.transit.arrivals is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit tfl.transit.arrivals? +

Yes. Add a rate_limit block to the tfl.transit.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.

How do I block tfl.transit.arrivals completely? +

Set action: deny in the PolicyLayer policy for tfl.transit.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.

What MCP server provides tfl.transit.arrivals? +

tfl.transit.arrivals is provided by the Apibase MCP server (apibase-mcp-client). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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