MBTA MCP Server

by cubismod

Overview Schema Source Related Servers Discussions Admin

Python

Remote

mbta_get_predictions

Retrieve real-time MBTA transit predictions for specific stops, routes, or trips to help plan travel.

Instructions

Get real-time predictions for MBTA services.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "mbta_get_predictions"
  }
}

Input Schema

Name	Required	Description
`stop_id`	No	Filter predictions by stop ID
`route_id`	No	Filter predictions by route ID
`trip_id`	No	Filter predictions by trip ID
`page_limit`	No	Number of results to return (default: 10)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0May 26, 2026

TDQS

C2.8/5.0

Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description must carry the full burden of behavioral disclosure. It only states 'Get real-time predictions' without mentioning pagination, rate limits, data freshness, or any other behavioral traits beyond the input schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is very concise at one sentence, but it lacks structure and important details. It could be expanded with usage notes without losing conciseness.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool has 4 parameters, no output schema, and no annotations, the description is too minimal. It does not explain the return format, pagination behavior, or other important context, making it incomplete for an agent to use effectively.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the input schema already documents all parameters. The description adds no additional meaning beyond what is in the schema, resulting in a baseline score of 3.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool retrieves real-time predictions for MBTA services, using a specific verb and resource. However, it does not differentiate from many sibling tools with similar prediction-related purposes.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance is provided on when to use this tool versus alternatives. For example, there are tools like mbta_get_predictions_for_stop and mbta_get_prediction_stats, but the description offers no context for selection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.