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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds that only *active* satellites are counted and that the filters narrow lists rather than returning everything, but it says nothing about data recency, truncation of the counts themselves, or cost/size of the response.

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 core purpose and the enumeration of dimensions are front-loaded in one dense sentence, followed by a short filter note. The category list is long but every item conveys a distinct aggregation, so little 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?

With no output schema, the description must convey what comes back; it does so by naming each count category, and the limit parameter's per-category meaning is covered by the schema. Output shape, ordering, and data freshness remain unspecified, which is a real but modest gap for a read-only statistics 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 100%, so baseline would be 3. The description goes beyond the schema by giving concrete value vocabularies (US, PRC, CIS, ESA; SpaceX, OneWeb, Amazon Kuiper; LEO/MEO/GEO/HEO) and by clarifying that filters may be given as code or name and act by narrowing a list — semantics the schema alone states only per-parameter.

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?

Opens with a specific verb+resource (counts of active satellites) and enumerates the aggregation dimensions: owner, operator, CelesTrak group, orbit regime, object type, launch year, recent launches and altitude bands. That is far more precise than its siblings (perigee_object, perigee_find), though it never explicitly contrasts itself with them.

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 second sentence explains that owner/operator/group filters narrow the corresponding list, which is useful context for how to call it. It does not say when to prefer this aggregate tool over object-level siblings such as perigee_find or perigee_orbit, so usage is only implied.

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