MBTA MCP Server

by cubismod

Overview Schema Source Related Servers Discussions Admin

Python

Remote

mbta_get_shapes

Retrieve route shape coordinates for MBTA transit lines to display on maps. Filter by route ID or shape ID.

Instructions

Get route shape/path information for mapping.

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_shapes"
  }
}

Input Schema

Name	Required	Description
`shape_id`	No	Specific shape ID to get
`route_id`	No	Filter shapes by route 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

C2.9/5.0

Behavior2/5

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

With no annotations, the description carries the full burden for behavioral disclosure. It only says 'for mapping,' which is vague. It does not mention data freshness, rate limits, required permissions (if any), or the response structure. For a tool returning geometric data, this is insufficient.

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

Conciseness4/5

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

The description is a single short sentence with no wasted words. It is front-loaded and easy to parse. However, it could be slightly more informative without becoming verbose.

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 absence of an output schema, the description should indicate what the response contains (e.g., points, polylines). It does not explain default behavior when no parameters are provided (e.g., returns all shapes or first 10). The complexity is low, but the description lacks critical details for a mapping tool.

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 description coverage is 100%, so baseline is 3. The description adds no extra meaning beyond the schema; it repeats the purpose but not parameter details. The schema itself is minimal (e.g., 'Specific shape ID to get'), and the description does not explain how parameters interact or typical use cases.

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 route shape/path information for mapping, using a specific verb 'Get' and resource 'route shape/path.' It distinguishes from siblings like mbta_get_routes which focus on route metadata, but could be more precise about what 'shape/path information' includes (e.g., polyline coordinates).

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 given on when to use this tool versus alternatives such as mbta_get_routes or mbta_get_trips. There is no mention of prerequisites, filtering strategies, or scenarios where this tool is preferred, leaving the agent without decision context.

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