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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered there. The description's added content is mostly a restatement of the return values, which the output schema already provides; it adds no new behavioral context such as calculation assumptions or limitations.

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 sentences, trigger examples front-loaded before the return list, with no filler. Slightly heavy on enumerating outputs that the output schema already covers, but still tight and readable.

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 two-input, read-only calculator with a complete output schema and full annotation coverage, the description supplies everything an agent needs to select and invoke it; return-value detail lives in the output schema as intended.

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%: the schema already documents the metric/flotation formats, P/LT prefixes, exclusion of load index and speed rating, and the default/range for speed_shown. The description only supplies illustrative examples of those same formats, so 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?

The description names a specific comparison operation between two tire sizes and enumerates the concrete outputs (diameter, width, sidewall, ride-height change, true speed, odometer error). This clearly separates it from siblings such as wheel_fitment_check or gear_ratio_calculator.

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?

Three natural-language example triggers ('what changes if I go from 265/70R17 to 285/75R17', 'how far off is my speedometer with 33s', odometer error) make the intended use case unmistakable. It does not, however, state when NOT to use it or name which sibling to prefer for fitment/clearance questions.

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