plan_route

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

Provides one behavioral detail: times are in seconds from midnight. Without annotations, more transparency is expected (e.g., rate limits, consequences of invalid inputs), but it is minimally informative.

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 concise sentences, no redundancy. The first sentence states purpose, the second adds critical output format detail. Every word earns its place.

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?

Given 14 parameters and no output schema, the description is insufficient. It lacks examples, response structure, or guidance on handling common cases. Only adds time unit info.

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 coverage is 57%, but the description does not add meaning beyond what the schema provides. It does not explain parameter usage or relationships, relying on the schema for details.

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 searches transit routes in Japan with specific search types (departure, arrival, first, last). It distinguishes from sibling tools like station_departures by focusing on route planning between locations.

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?

No guidance on when to use this tool versus alternatives such as station_departures or guidance_plan. The description lacks comparisons or context for tool selection.

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