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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, covering the safety profile. The description adds value by enumerating the specific returned parameters (orbital period, radius, mass, etc.) and the data source, which helps an agent understand what 'full parameters' means. No contradiction.

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?

Three sentences, each earning its place: the core action, the return content, and example names. 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 one parameter, comprehensive annotations, and an output schema, the description is complete. It lists the key return fields, gives example names, and clearly identifies the data source, so an agent can invoke it correctly.

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?

The schema description already covers the planet_name parameter with examples, and coverage is 100%. The description repeats the 'exact name' requirement and examples but does not add new semantic information beyond the schema.

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 ('Get'), a specific resource ('full parameters for a specific exoplanet'), and the key constraint ('by exact name'), clearly distinguishing it from sibling search tools like nasaexoplanet.planets.search. It also provides concrete example names to disambiguate the expected input format.

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?

The phrase 'by exact name' establishes when to use this tool, and the example names reinforce that. However, it does not explicitly name alternative tools or state when not to use it, leaving the contrast with search tools implicit rather than stated.

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