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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world behavior, so the safety profile is covered. The description usefully adds the return shape, but says nothing about edge cases such as the exclusiveMinimum constraint on value or behavior with invalid units.

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 compact sentences with the conversion scope front-loaded and the return shape inline. Nothing is wasted, though the trailing cross-reference to list_bundles is of marginal value to the calling agent.

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, fully documented converter with an output schema and complete annotations, the definition covers what is needed to invoke it correctly. The only shortfall is the missing differentiation from near-identical sibling tools.

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 the schema already documents both parameters and the unit enum. The description restates the same unit set and mirrors the return keys without adding syntax, defaults, or meaning beyond what the schema provides.

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 and resource: converts astronomical distances between light-years, parsecs, AU, and km. The scope is unambiguous, but the description never distinguishes this tool from near-duplicate siblings such as calculate_light_year or convert_distance, so an agent cannot tell them apart from the text alone.

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?

There is no statement of when to use this tool versus the alternatives, despite two closely related siblings (calculate_light_year, convert_distance) existing. The only pointer, 'See list_bundles for related astronomie-nature calculators', is a cross-reference to a browsing tool, not usage guidance.

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