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

Beyond the annotations, the description discloses the fare model components (billable hours including roll-call, billable km including empty running, night hours, relief-driver flags). It also states the conditional return behavior and clearly warns that the result is never a confirmed price, which is important behavioral context not covered by the 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?

The description is two dense but well-structured sentences, front-loading the calculation purpose and then the return conditions. Every phrase contributes useful information without unnecessary repetition.

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?

For a fare-estimation tool with no output schema, the description sufficiently explains the calculation basis, output type, and conditional 'quote_required' status. The main remaining gap is that it does not explicitly route the agent to create_quote_request when a quote is required, though the status name strongly hints at that next step.

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 100%, so the input schema already explains vehicle_id, days, vehicles, and locale. The description adds fare-system context around billable hours and kilometers, but does not add parameter-specific meaning beyond what the schema provides; baseline 3 is appropriate.

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 a specific verb and resource: it calculates charter bus fare structure under Japan's time + distance system. It distinguishes the output as a reference estimate rather than a confirmed price, but does not explicitly name or contrast with sibling tools such as create_quote_request.

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 implies when the tool is usable by saying it returns a yen estimate only when the rate table is verified and all routing inputs are present, otherwise 'quote_required'. It does not explicitly say when to use this tool versus create_quote_request or get_quote_status, leaving the alternative path implicit.

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