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

Annotations already declare readOnlyHint and openWorldHint, and the description adds real content: it enumerates exactly what the response will contain, including fetch timestamps, typical accuracy, catalogue sizes, reference frame, attribution and an educational-use disclaimer. Since there is no output schema, this enumeration is the main disclosure of return content and it does that job well, though it says nothing about format or size.

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?

A single front-loaded sentence with no filler; the colon-list packs in all the relevant content categories efficiently. It is slightly dense/listy, but nothing is wasted.

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?

For a zero-argument, read-only reference tool with no output schema, the description covers what an agent needs: what information is returned and why it matters (provenance, accuracy, attribution, disclaimer). Only minor gaps remain around response shape and whether the content is static or timestamp-dependent.

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 tool takes zero parameters, so the baseline is 4. The description correctly implies no input is needed to retrieve this static reference information.

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 makes clear this is a metadata/provenance endpoint: 'data sources and when they were fetched, the models and their typical accuracy, catalogue sizes, frame, attribution...'. That distinguishes it from the computational siblings (perigee_orbit, perigee_passes, etc.) which return derived results rather than source documentation. It is framed as content ('what every answer rests on') rather than as a verb like 'returns', which keeps it just short of a 5.

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?

Use is only implied: an agent can infer it should call this when it needs to cite provenance, accuracy caveats, or attribution. There is no explicit 'call this when...' or 'do not use for X' guidance, and no alternative is named, which is acceptable given no sibling overlaps in scope.

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