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Transit stops near a point

transit_stops_near
Read-onlyIdempotent

Nearest transit stops to a point, nearest first — bus, rail, subway, tram, ferry.

Instructions

Nearest transit stops to a point, nearest first — bus, rail, subway, tram, ferry.

A filtered view over Overture's base/infrastructure `subtype='transit'`
rows (the same theme infrastructure_at reads), restricted to real,
boardable stop classes: bus_stop, bus_station, railway_station,
railway_halt, subway_station, tram_stop, ferry_terminal,
aerialway_station. Unfiltered, that layer is dominated by
bicycle_parking and by platform/stop_position — OSM's per-geometry
re-tagging of the same physical stop — which this tool never returns
by default; if zero stop-class rows are within radius_m it falls back
to platform/stop_position rows instead of an empty answer, and says so
in "note". `kind` restricts the search to exactly one class (any of
the stop classes above, or "platform"/"stop_position" directly);
an unrecognized kind returns a bad_request naming the accepted values.

Returns {"center", "radius_m", "results": [{"id", "kind", "name",
"distance_m"}, ...], "total_in_range"}, plus "truncated": true and an
explanatory "note" whenever fewer rows came back than matched, and a
"note" when the fallback fired or the search found nothing at all. id
is the GERS id, usable with other GERS-keyed tools. No raw geometry and
no schedules or live arrivals — Overture base/infrastructure is a
static OpenStreetMap conflation, and neither exists in it even in
principle; a caller wanting "next bus" needs a live transit API.

An empty results list is a valid answer, not an error: base-theme
coverage is OSM-derived and patchy, and "no stop within radius_m" is a
real finding. radius_m echoes the effective radius, which may be lower
than requested (large values are clamped).

Returns a structured {"error": ...} if upstream is unavailable or the
dataset is missing geometry/bbox, and {"error": "bad_request"} for a
non-finite or out-of-range coordinate, or an unrecognized kind.

Input Schema

NameRequiredDescriptionDefault
latYes
lonYes
kindNo
limitNo
radius_mNo

Output Schema

NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv0.11.0

TDQS

A4.6/5.0
Behavior5/5

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

Beyond the annotations (which only cover the safe-read profile), the description discloses substantial behavior: default exclusion of bicycle_parking and platform/stop_position, a fallback to platform/stop_position when zero stop-class rows exist, truncation signaling, radius clamping, empty results being valid, and structured error shapes. This is exactly the extra context annotations cannot provide.

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?

Purpose is front-loaded in the first sentence and the detail is information-dense rather than padded. It is longer than typical and repeats the fallback/note and error behaviors in more than one place, but the length is largely justified by the complex fallback and error contract.

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

Completeness5/5

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

For a tool with five parameters, a fallback path, truncation semantics, and clamping behavior, the description covers the decisions an agent must make (empty-result validity, fallback caveats, error conditions, no live arrivals). It even documents the return shape despite an output schema existing, so nothing material is missing.

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

Parameters4/5

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

With 0% schema description coverage, the description has to carry parameter meaning, and it does for kind (exhaustive accepted values plus the bad_request behavior on unrecognized input) and radius_m (echo may be lower than requested due to clamping). lat/lon are self-evident, but 'limit' is never mentioned despite appearing in the schema, leaving one parameter undocumented.

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

Purpose5/5

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

The opening sentence states a specific verb+resource ('nearest transit stops to a point') with ordering ('nearest first') and the covered modes. It further distinguishes itself from the sibling 'infrastructure_at' by explaining that it is a filtered view over the same base/infrastructure theme, so an agent can route between the two without opening either schema.

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

Usage Guidelines4/5

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

It gives clear conditions for use (point + radius, optional single-class filtering via kind) and an explicit exclusion: a caller wanting 'next bus' needs a live transit API, since schedules/arrivals are not in this dataset. It stops short of naming a specific sibling to prefer under a given condition, so it is a strong 4 rather than a 5.

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