# mbta.transit.predictions

Get real-time arrival and departure predictions for Boston MBTA stops — live vehicle tracking data for subway, bus, commuter rail, and ferry. Returns predicted arrival_time, departure_time (ISO 8601), direction, status (e.g. "Boarding"), schedule relationship (SCHEDULED/SKIPPED/NO_DATA), and associated route, stop, trip, and vehicle IDs. Requires at least one filter: stop ID (e.g. "place-sstat" for South Station, "place-pktrm" for Park Street) or route ID. Use direction_id to filter inbound (1) vs outbound (0). MassDOT Open Data License, real-time live data, no upstream cost.

Agent View of the PolicyLayer registry record for `mbta.transit.predictions`. HTML page: https://policylayer.com/tools/io-github-whiteknightonhorse-apibase/mbta.transit.predictions

## Facts

- Tool: `mbta.transit.predictions`
- Server: Apibase (`apibase-mcp-client`) — https://policylayer.com/tools/io-github-whiteknightonhorse-apibase.md
- Install: `npx -y apibase-mcp-client`
- Homepage: https://github.com/whiteknightonhorse/APIbase
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 4
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `stop` | string | no | Stop or station ID for arrival/departure predictions (e.g. "place-sstat" for South Station, "place-pktrm" for Park Street). Use mbta-transit.stops to find stop |
| `limit` | integer | no | Maximum number of predictions to return (default 10, max 50). Each prediction is one scheduled stop for one vehicle. |
| `route` | string | no | Route ID to get predictions for (e.g. "Red", "Green-B", "1"). At least one of stop or route is required. |
| `direction_id` | integer | no | Filter by direction: 0=outbound (away from downtown/terminus), 1=inbound (toward downtown/terminus). See mbta-transit.routes for direction names. |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "mbta.transit.predictions",
    "arguments": {}
  }
}
```

## Why mbta.transit.predictions is rated Low

Tool queries public transit data without modifying state or executing external operations.

From the tool's own definition: "Get real-time arrival and departure predictions, live vehicle tracking data, returns predicted times and IDs"

## Use case

AI agents call mbta.transit.predictions to retrieve information from Apibase without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Apibase:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "mbta.transit.predictions": {}
  }
}
```

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## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=io-github-whiteknightonhorse-apibase · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-github-whiteknightonhorse-apibase