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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds useful context beyond those annotations: the output is 'bounded' and 'aggregate,' and it applies to the 'current public aircraft snapshot,' so the agent should not expect a full aircraft list. No contradiction exists.

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 description is a single sentence, front-loaded with 'Return,' and contains no filler. Every word contributes meaning about the tool's scope and output.

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-parameter read-only tool, the description is nearly complete: an agent knows it will receive bounded aggregate counts for the current snapshot. However, since there is no output schema, the description could be slightly more explicit about what dimensions the counts cover (e.g., total aircraft, counts by type), preventing a perfect 5.

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 has zero parameters and the input schema is trivial, so there is no parameter meaning for the description to add. This is the baseline-4 case for parameterless tools; no information is missing.

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, 'Return', and names a clear resource: 'bounded aggregate counts for the current public aircraft snapshot.' It also distinguishes itself from the sibling tools get_aircraft and nearby_aircraft by returning statistics rather than aircraft records.

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 usage is implied by 'bounded aggregate counts'—an agent can infer to use this when aggregate snapshot statistics are needed—but there is no explicit when-to-use vs alternatives guidance. The sibling tools are never named or contrasted in the description.

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