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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds the '2 of 3 inputs' constraint, but the trailing 'Returns: {error}' is confusing/partial when a full output schema exists and provides no real behavioral insight.

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 short sentences, front-loaded with the core operation and the input rule. 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?

With annotations covering safety and an output schema covering return values, the description needn't explain results. It covers the key input constraint adequately; the only weak spot is the odd 'Returns: {error}' fragment, which is not harmful but adds little.

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 units documented (km/h, kilometers, minutes), so the schema carries most of the burden. The description adds genuine meaning the schema lacks: the schema marks 0 parameters required, so stating that exactly 2 of 3 must be supplied is a real constraint beyond structured data.

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+resource ('Solve speed/distance/time') and the exact input condition ('provide any 2 of 3 values'). It is distinguishable from convert_speed, though it doesn't explicitly name sibling calculators beyond pointing to list_bundles.

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?

Gives implicit usage guidance via the '2 of 3 values' input rule and a cross-reference to list_bundles for related sport calculators, but never states when to prefer this tool over convert_speed or other physics/motion siblings, nor any exclusions.

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