Find a bus or train

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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds useful behavioral context by specifying the return data (GPS coordinates, heading, speed, occupancy, next scheduled stop) and noting that the stop is included 'when available'. It does not contradict annotations, and the mention of 'when available' aligns with the open-world hint. However, it does not disclose behavior such as what happens when no match is found or whether both vehicle and route are allowed.

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?

The description is two sentences, front-loaded with the primary purpose and immediately followed by usage examples. Every word contributes to understanding the tool's behavior and parameters. There is no redundant or filler content.

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?

The description covers the main usage patterns (vehicle- and route-based lookup) and mentions the output fields. However, it does not specify behavior when both vehicle and route are provided, when neither is provided, or how the mode parameter applies. Given the existence of an output schema, the missing parameter-precedence details are a gap that could lead to incorrect usage.

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?

The input schema already provides descriptions for all three parameters (mode, route, vehicle). The description adds extra meaning by explaining the mutually exclusive use of vehicle vs. route ('Give vehicle for a vehicle number... or route to get every vehicle'). It does not clarify the mode parameter or interaction between fields, so the added value over the schema is limited.

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?

The description starts with a specific verb ('Locate'), names the resource ('a specific CATS bus or train'), and states the output ('current GPS coordinates'). It also distinguishes two search modes (by vehicle number or by route) and clarifies the scope ('every vehicle currently running a route'). This clearly differentiates it from siblings like list_vehicles and get_arrivals, which likely list all or handle scheduled times.

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?

The description gives parameter usage instructions ('Give vehicle for a vehicle number... or route to get every vehicle') but provides no guidance on when to choose this tool over list_vehicles or get_arrivals. It does not mention exclusions, alternatives, or when the tool is not appropriate, leaving the agent to infer tool selection from the name alone.

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