onebusaway-mcp-server

Get Real-Time Vehicle Positions

onebusaway_get_vehicles

Read-only

Real-time positions of all active vehicles for an agency. Optionally filter to a single route (client-side). Returns GPS coordinates, heading, schedule deviation, and current trip. Useful for "where are all the buses on route X right now?" Use agencyId values from onebusaway_list_agencies.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`routeId`	No	Optional agency-prefixed route ID to filter results to one route. Filtering is client-side — all agency vehicles are fetched first.
`agencyId`	Yes	Agency ID (e.g. "1" for Metro Transit, "40" for Sound Transit). Use onebusaway_list_agencies to discover IDs.

Output Schema

TableJSON Schema

Name	Required	Description
`count`	No	Number of vehicles returned after any route filter.
`error`	No	Present when the call failed. Absent on success.
`notice`	No	Guidance when no vehicles were found — e.g. the route may not be currently active, or the agency may not have real-time data.
`routeId`	No	Route ID filter applied client-side, if any.
`agencyId`	No	Agency ID queried.
`vehicles`	No	Active vehicles for the agency, optionally filtered by route.
`limitExceeded`	No	True if the upstream capped the vehicle list — some vehicles were omitted. This endpoint has no pagination to retrieve them.

Schema Changelog

Changes observed during successful MCP inspections.

Changed16 schema fields changedSep 19, 2026

changedOutput schema / properties / error / properties / data / properties / reason / description

Previous value: -"Machine-readable failure mode. Declared by this tool: `agency_not_found`: Agency ID does not exist on this instance. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `agency_not_found`: Agency ID does not exist on this instance. `rate_limited`: No upstream request slot opened within the queue wait cap, or OneBusAway returned a rate limit response. Other values are possible when a failure originates below the handler."

changedOutput schema / properties / error / properties / data / properties / reason / examples

Previous value: -[
-  "agency_not_found"
-]New value: +[
+  "agency_not_found",
+  "rate_limited"
+]

removedOutput schema / properties / vehicles / items / properties / nextStop / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / vehicles / items / properties / nextStop / type
```
Added value: +[
+  "string",
+  "null"
+]
```
removedOutput schema / properties / vehicles / items / properties / orientation / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
addedOutput schema / properties / vehicles / items / properties / orientation / type
```
Added value: +[
+  "number",
+  "null"
+]
```

removedOutput schema / properties / vehicles / items / properties / routeId / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / vehicles / items / properties / routeId / type
```
Added value: +[
+  "string",
+  "null"
+]
```
removedOutput schema / properties / vehicles / items / properties / routeShortName / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
addedOutput schema / properties / vehicles / items / properties / routeShortName / type
```
Added value: +[
+  "string",
+  "null"
+]
```
removedOutput schema / properties / vehicles / items / properties / scheduleDeviation / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
addedOutput schema / properties / vehicles / items / properties / scheduleDeviation / type
```
Added value: +[
+  "number",
+  "null"
+]
```
removedOutput schema / properties / vehicles / items / properties / tripHeadsign / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
addedOutput schema / properties / vehicles / items / properties / tripHeadsign / type
```
Added value: +[
+  "string",
+  "null"
+]
```

removedOutput schema / properties / vehicles / items / properties / tripId / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

addedOutput schema / properties / vehicles / items / properties / tripId / type
```
Added value: +[
+  "string",
+  "null"
+]
```

Changed6 schema fields changedAug 24, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "vehicles",
+      "limitExceeded",
+      "agencyId",
+      "count"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `agency_not_found`: Agency ID does not exist on this instance. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "agency_not_found"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "vehicles",
-  "limitExceeded",
-  "agencyId",
-  "count"
-]

Changed2 schema fields changedJul 13, 2026

addedOutput schema / properties / limitExceeded

Added value: +{
+  "description": "True if the upstream capped the vehicle list — some vehicles were omitted. This endpoint has no pagination to retrieve them.",
+  "type": "boolean"
+}

changedOutput schema / required

Previous value: -[
-  "vehicles",
-  "agencyId",
-  "count"
-]New value: +[
+  "vehicles",
+  "limitExceeded",
+  "agencyId",
+  "count"
+]

Changed5 schema fields changedMay 30, 2026

addedOutput schema / properties / agencyId

Added value: +{
+  "description": "Agency ID queried.",
+  "type": "string"
+}

addedOutput schema / properties / count

Added value: +{
+  "description": "Number of vehicles returned after any route filter.",
+  "type": "number"
+}

addedOutput schema / properties / notice

Added value: +{
+  "description": "Guidance when no vehicles were found — e.g. the route may not be currently active, or the agency may not have real-time data.",
+  "type": "string"
+}

addedOutput schema / properties / routeId

Added value: +{
+  "description": "Route ID filter applied client-side, if any.",
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "vehicles"
-]New value: +[
+  "vehicles",
+  "agencyId",
+  "count"
+]

First observedMay 25, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations declare readOnlyHint=true, so the safe-read nature is already captured. The description adds meaningful behavior beyond that: filtering is client-side (all agency vehicles are fetched first), and the tool returns GPS coordinates, heading, schedule deviation, and current trip. This gives the agent expectations about data volume and output content without contradicting the annotation.

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

Conciseness5/5

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

The description is compact and front-loaded: it states the core function, filter option, return content, a typical use case, and where to find agency IDs. Every sentence earns its place, with no redundancy or filler.

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

Completeness4/5

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

With an output schema present, the return structure does not need to be fully explained in the description. The description covers the required agencyId source, optional route filtering, and the nature of the data. Minor gaps such as pagination or data freshness are not critical because the output schema provides response detail and the tool is read-only.

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?

Schema coverage is 100%, so the schema already describes both parameters. The description adds value by giving example agency IDs ('1' for Metro Transit, '40' for Sound Transit) and by explicitly stating the route filter is client-side, meaning all vehicles are fetched before filtering. This helps an agent understand practical implications beyond the schema's basic field definitions.

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 description states a specific verb and resource: 'Real-time positions of all active vehicles for an agency.' It clearly distinguishes itself from siblings by focusing on live vehicle positions, and lists concrete output fields (GPS coordinates, heading, schedule deviation, current trip). This is unique among the sibling tools, none of which cover real-time vehicle tracking.

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?

The description gives clear context by framing the tool as useful for 'where are all the buses on route X right now?' and explicitly directs the agent to get agencyId values from onebusaway_list_agencies. It also explains the optional route filter, including the client-side behavior. It does not explicitly name alternative tools or exclusions, but no sibling offers the same real-time vehicle capability, so the guidance is sufficient.

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

All onebusaway-mcp-server tools Inspect

Try in Browser

One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.