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

Annotations already cover safety (readOnly, idempotent, non-destructive, openWorld), so the description's real contribution is data provenance and payload shape: GCAT for record fields, SatNOGS for TLE, and computed position with lat/lon/altitude/speed/period plus element age. It omits what happens on no match or on ambiguous name matches, which is the main remaining 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?

Front-loaded with the resource and accepted identifier forms, then the answer keys, with no filler sentences. The '[NicheDB]' prefix and the 'Served by NicheDB (https://...)' footer are boilerplate that does not help an agent decide or invoke.

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 correctly carries the return-value burden by enumerating the four answer keys and their contents. It falls short only on edge behavior — no-match handling, name ambiguity, and freshness of position beyond 'how old the elements are'.

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% and the single `query` parameter is already documented with an example, so the baseline is 3. The description adds modest value by supplying a concrete international-designator format (1998-067A) that the schema example does not illustrate.

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 ('lookup') and resource (satellite, rocket stage or debris), plus exactly which identifiers are accepted (NORAD number 25544, international designator 1998-067A, or name). The domain is unambiguous versus the airplane/ship/train/vuln lookup siblings, so an agent can route to it without reading the schema.

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?

Usage is implied rather than stated: the description never says when to prefer this tool or when not to use it, and the one hint ('`matches` for a designator or name') is about response behavior, not tool selection. The parenthetical examples do make the accepted query forms self-evident, which keeps it above a 2.

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