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

Annotations already mark the operation read-only and idempotent, so the description adds value by disclosing specific behavior: refusal when any non-personal trip is unpriced, oldest-first ordering, and the bare-number amount format for spreadsheet compatibility. These traits go well beyond the annotation hints and shape caller expectations.

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 dense but efficient. Every clause contributes meaning: column list, ordering, rate context, amount formatting, and refusal condition. It is front-loaded with the core purpose and contains no filler.

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 read-only export with no output schema, the description covers output format, ordering, column semantics, and failure mode. It leaves minor gaps such as whether a header row is included or what happens when the date range has no trips, but these are not critical for correct invocation.

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 100%, with both parameters already described with format and defaults. The description adds the concept of a 'window' but no parameter-specific detail beyond what the schema already provides, so the baseline of 3 applies.

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 identifies a precise verb+resource: exporting the mileage log as CSV. It enumerates every column and explicitly orders rows oldest first, distinguishing it from sibling tools like mileage_summary and trip_list by the one-row-per-trip CSV format.

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?

'Export the log as CSV for an accountant' establishes a clear use case. The description implies when to use it, but it does not explicitly state when not to use it or name alternatives such as mileage_summary for aggregated totals.

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