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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive hints. The description adds useful behavioral context: it returns specific fields (orbital period, radius, mass, equilibrium temperature, discovery year and facility, system distance), mentions the scale (6,298+ planets), and notes the surveys (Transit, Radial Velocity, Imaging, Microlensing). This goes beyond annotations without contradicting them.

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 sentences, front-loaded with the core action and filters, then the return fields, then a scale note. No fluff, each sentence earns its place. It is well-structured for quick scanning.

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?

Given the tool has 10 optional parameters and an output schema, the description is sufficiently complete for an agent to understand its purpose and what it returns. It could benefit from a note about how to combine filters or when to use sibling tools, but those gaps are minor since the schema and output schema cover the technical details.

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 descriptions for all parameters, including examples for mass and radius. The description's list of filters mirrors the parameters without adding new semantic detail beyond the schema. It does not clarify how to combine filters or provide additional context on parameter usage beyond what's already in 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 clearly states the tool searches the NASA Exoplanet Archive for confirmed exoplanets, lists the specific search dimensions (name, host star, discovery method, year range, radius, mass), and differentiates itself from sibling tools like detail, habitable, and stats by emphasizing 'search' and returning a set of properties. This is a specific verb+resource with clear scope.

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 description implies this is the general search tool, while siblings like detail, habitable, and stats serve other purposes, but it does not explicitly state when to prefer this tool over alternatives or when not to use it. The guidance is implied by the name and description, not explicit.

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