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

Annotations establish the write profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false). The description adds real behavioral context beyond that: IRS rate calculation tied to the trip date and a confirm/idempotency mechanism. The 'idempotency validation' phrasing sits against idempotentHint=false, but the opt-in idempotencyKey parameter explains it, so this is not a true contradiction.

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 tight sentences with the core capability front-loaded and no filler. The second sentence ('Supports confirm and idempotency validation') is slightly vague but still earns its place by flagging the dry-run mechanism.

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 an 11-parameter write tool with no output schema, the description covers the essential behaviors (IRS calculation, dry-run/commit, idempotency) and annotations cover the safety profile. It stops short of explaining what a dry-run preview returns or what side effects a commit produces, leaving some gaps for a mutation tool.

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 all 11 parameters are already documented, including confirm (dry-run vs commit), idempotencyKey, and the enum category. The description reinforces the date/IRS and confirm concepts but adds no syntax or format detail beyond what the schema already supplies, so the baseline 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?

States a specific verb (log) applied to a specific resource (vehicle travel trip) and adds the differentiating feature of automatic IRS rate calculations. It implicitly separates itself from the read-only sibling get_mileage_logs, though it never names that sibling explicitly.

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 mention of 'confirm' and 'idempotency validation' hints at a dry-run-then-commit workflow, but there is no explicit when-to-use guidance, no statement of prerequisites, and no reference to alternative tools. Usage is left to inference from the parameter names.

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