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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful content context (645,000+ count, breakdown dimensions, keywords) and corpus-wide scope, but discloses no additional behavioral traits such as pagination, rate limits, or response size. This matches the calibration bar: annotations carry safety, description adds some but not rich behavioral context.

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?

Four sentences, with the core action front-loaded and each subsequent sentence earning its place: return dimensions, keywords, and usage context. It is slightly more verbose than strictly needed due to the enumerated breakdown lists, but there is no padding or repetition.

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?

Tool complexity is low (one optional parameter), an output schema exists, and annotations fully cover the safety profile. The description's 'entire corpus' framing plus the detailed return-content list is enough for an agent to decide when to call it versus related nasantrs tools. Minor gap: it doesn't explicitly contrast with the sibling detail/search/recent tools, but the scope language makes the distinction sufficiently clear.

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 description coverage is 100%, and the single 'detail' parameter is already fully documented in the schema, including the note that it is 'Always true — parameter reserved for future use.' The description adds no parameter-level meaning beyond the schema, so the baseline 3 applies.

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 opens with a specific verb and resource: 'Get aggregate statistics for the entire NASA Technical Reports Server corpus.' The 'entire corpus' scope and 'aggregate statistics' framing clearly distinguish it from siblings nasantrs.reports.search, nasantrs.reports.detail, and nasantrs.reports.recent, which operate on individual reports or filtered sets.

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 closing sentence 'Useful for understanding the scope and distribution of NASA's documented research output' provides clear context for when this tool is appropriate. However, it doesn't explicitly name alternatives or state when-not-to-use it (e.g., when needing a specific report, use nasantrs.reports.detail), so it stops short of full exclusion guidance.

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