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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false. The description adds real value beyond that: it states no authentication is required, that no account data is read or saved, and that actual mounted diameter varies by tire model and pressure. These auth and accuracy caveats are exactly the behavioral context annotations cannot convey.

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?

Four sentences, front-loaded with the computed outputs, then the auth/data-access note, then two accuracy caveats. Every sentence carries information and nothing is padded, though the auth clause is slightly tangential to the core comparison function.

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?

An output schema exists, so return values need no explanation, and annotations cover the safety profile. With all 7 parameters fully described in the schema and the description covering purpose, auth behavior, and accuracy limitations, an agent has what it needs, though no explicit sibling routing is provided.

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%, with every one of the 7 parameters documented including units, exclusiveMinimum/maximum bounds, and the unitSystem enum. The description adds no additional parameter meaning beyond the schema, 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 states a specific verb (compare) and resource (tire sizes) and enumerates the exact outputs computed: diameter, circumference, ride height, and speedometer change. It clearly separates this from sibling calculate_* tools by naming the tire-size domain, though it does not explicitly name an alternative tool.

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?

'Use manufacturer specs when available' implies this is an approximation tool to be preferred only when specs are unavailable, which is useful implied guidance. However, it never explicitly states when to choose this over siblings like calculate_tire_pressure_adjustment or analyze_tire_temperatures, so guidance remains implicit rather than explicit.

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