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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description adds genuinely new behavioral detail — multilingual matching, optional accents, and accepted identifier schemes (NORAD, COSPAR). It does not state what happens with ambiguous or zero matches (multiple results, empty set), which is the main remaining behavioral gap.

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?

One dense sentence that front-loads the verb and the accepted input formats, with the return value last. Every clause earns its place; only the missing `limit` mention keeps it from being complete rather than verbose.

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 no output schema, the description should say more about the return shape than 'returns ids' — whether it returns one or many matches, and what fields accompany each. The unaddressed `limit` parameter compounds this, though the input-format guidance is strong for a discovery 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?

Schema coverage is 0%, so the description must carry parameter meaning. It richly characterizes `query` (names or identifiers, English/French, accents optional, multiple id formats) but never mentions `limit` (1-50) — whether it caps matches or is a fuzzy-match threshold is left entirely to guesswork.

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?

A specific verb ('looks up') plus an enumerated set of resources (planets, moons, missions, satellites, sites, stars) makes the scope unmistakable. It also states the return value's role ('Returns ids for the other tools'), which implicitly separates it from perigee_object and perigee_state, though no sibling is named directly.

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?

'Returns ids for the other tools' implies this is a resolution step before calling id-based tools, which is useful implied usage. There is no explicit when-not or named alternative (e.g. when to prefer perigee_object if you already have an id), so selection still requires inference.

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