find_buses_by_arrival_time

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

No annotations are provided, so the description carries the burden. It discloses that it finds scheduled (not live) buses and specifies time format. However, it does not describe behavior on errors, missing stops, or invalid input. It adds some value but is not exhaustive.

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 a single sentence stating purpose followed by a clear bullet list of parameters. It is front-loaded and every sentence adds value. No superfluous text.

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?

With an output schema present, no need to explain return values. The description covers all parameters and notes that it finds scheduled (not live) buses. It does not mention prerequisites or error handling, but for a simple query tool this is adequate.

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?

Schema description coverage is 0%, so the description must add meaning. It does so effectively: stop_a is 'Boarding stop (NaPTAN code or name)', stop_b is 'Alighting stop', arrive_by is 'Target arrival time (HH:MM, 24h format)', and day is optional with specific day abbreviations. This significantly clarifies parameter meaning beyond the schema's minimal titles.

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 clearly states 'Find scheduled buses that board at stop_a and arrive at stop_b by the given time.' This uses a specific verb ('find'), a defined resource ('scheduled buses'), and specific constraints (boarding and alighting stops, arrival time). It distinguishes from siblings like 'find_routes_between_stops' and 'get_live_buses_on_route'.

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 lists parameters and implies usage for scheduled bus lookup, but it does not explicitly state when to use this tool versus alternatives. It mentions a default for 'day' but lacks guidance on exclusions or when not to use.

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