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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description goes beyond them by disclosing the ordering ('oldest first'), the exact output fields, and the non-obvious pricing behavior: each trip earns an amount under the day's rate, or shows a plain reason when unpriced. This is substantial behavioral context not available from annotations or schema.

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 sentences with no filler. Action, resource, ordering, output fields, and filtering capability are all front-loaded. 'Reads only' is a short reinforcement of annotations and does not bloat the text. Every sentence 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?

For a 3-parameter, read-only list operation with fully documented schema and strong annotations, the description covers everything needed to call it correctly: what is returned, in what order, how pricing is calculated, and what happens for unpriced trips. No output schema exists, but the field list in the description compensates adequately.

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?

The schema describes all three parameters at 100% coverage with formats and inclusive date semantics. The description merely restates that filtering by date range and category is possible, adding no new format, enum, or default information. This meets the baseline for full schema coverage without adding parameter-specific value.

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 states a specific verb ('List'), a specific resource ('trips in the mileage log'), and enumerates the exact fields returned with ordering ('oldest first'). This clearly distinguishes it from sibling tools like mileage_summary or mileage_export, which serve different aggregation/export purposes, even without naming them 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 description implies usage context via 'List trips...' and 'Filter by date range and category,' but it does not explicitly say when to prefer this tool over alternatives such as mileage_summary, mileage_export, or trip_add. There is no when-not-to-use guidance, so an agent must infer the appropriate choice from the resource type alone.

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