bus_predictionsFetch real-time next-bus arrival predictions for a WMATA bus stop by stop_id. Returns route ID, direction text, vehicle ID, and minutes until arrival.
| Name | Required | Description | Default |
|---|---|---|---|
| stop_id | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections. Dates show when Glama detected each change.
Input schema / examplesAdded value: +[
+ {
+ "stop_id": "1001234"
+ }
+]Output schema / (root)Previous value: -nullNew value: +{
+ "description": "Response from WMATA bus predictions API",
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover readOnly, idempotent, non-destructive. Description adds return fields (route ID, direction, etc.) beyond annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences, no fluff, front-loaded with action and output.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Adequate for a simple read-only tool with output schema; lacks error handling or rate limits but not critical.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Only parameter stop_id is mentioned but not described in format or source; schema coverage 0% and description minimally adds 'by stop_id'.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
Description clearly states the tool fetches real-time next-bus arrival predictions by stop_id, distinguishing it from siblings like bus_stops or bus_route_details.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Implied use case for real-time predictions, but no explicit when-to-use or when-not-to-use compared to alternatives like bus_incidents or rail_predictions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.