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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered. The description adds the gravity-ratio method and a related-bundle pointer, but its return claim ('weight on each planet') conflicts with the required single-planet enum, so the added behavioral signal is partly muddled.

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 three short sentences with the purpose front-loaded, which is appropriate for a simple calculator. The 'See list_bundles' sentence earns its place as related-tool routing, though the misleading 'each planet' return claim adds semantic noise.

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-parameter, low-complexity tool with an output schema and rich annotations, the description covers purpose, usage contexts, and related-bundle discovery adequately. The one gap is the omitted required `planet` parameter, though the 100%-covered schema compensates.

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 both `earth_weight_kg` and `planet` are documented in the schema and the baseline is 3. The description mentions only 'weight on Earth (kg)' and omits the required `planet` enum entirely, adding no meaning and potentially suggesting that no planet selection is needed.

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 gives a specific verb+resource: 'Compute your weight on other planets using gravity ratios.' However, it claims the tool 'Returns weight on each planet of the solar system' while the schema requires a single `planet` enum, so the output scope is misstated. There is also no explicit differentiation from the hundreds of sibling calculators beyond the implied astronomy domain.

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 for fun, education, sci-fi' provides broad usage contexts, which is more than nothing, but there is no when-to-use vs when-not-to-use guidance and no alternatives named. The 'See list_bundles' pointer is a discovery aid, not a signal for choosing this tool over another.

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