list_visible_planets

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

With no annotations, the description fully describes the input parameters and the output structure (dict with 'data' and '_meta', each planet having name, altitude, azimuth). It clearly states the tool returns only planets above the horizon. However, it does not address edge cases like no visible planets or invalid coordinates.

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 concise and well-structured, with a clear purpose statement followed by a structured list of arguments and return type. Every sentence is informative without redundancy.

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?

The description covers the essential input and output details, including the structure of the return data. It is missing some specifics about the '_meta' field and potential error handling, but overall it is sufficient for a simple listing tool.

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 description adds meaningful context beyond the schema: units ('degrees'), time format ('YYYY-MM-DD HH:MM:SS'), and timezone type ('IANA timezone string'). This compensates for the 0% schema description coverage, though it could include validation constraints.

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 uses a specific verb 'Get' and clearly identifies the resource as 'list of solar system planets currently visible (above horizon)', which distinguishes it from siblings like get_celestial_pos and get_celestial_rise_set that deal with arbitrary celestial objects.

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 does not provide any guidance on when to use this tool versus alternatives. It lacks explicit when-to-use or when-not-to-use instructions, leaving the agent to infer from the tool's purpose alone.

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