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

Annotations already cover read-only/open-world/non-destructive, and the description adds substantial value beyond them: the 17 supported registers, the acceptance of international marks, the make_model_id/avionics_ids outputs, and the non-US registration_authority block plus FAA-only jurisdiction caveat for faa_ads/faa_stcs.

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 purpose, then acceptance, outputs, workflow position, and the jurisdiction caveat — all earning their place. The final sentence is long and run-on, slightly hurting readability, so not a full 5.

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?

An output schema exists, yet the description still usefully characterizes the key return fields; combined with the international-register and jurisdiction nuances, an agent has everything needed to invoke and interpret this tool correctly.

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 is 3, but the description adds breadth to the parameter beyond the schema's single example by enumerating four international format examples and the register count, reinforcing that non-US marks are valid input.

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+resource (look up aircraft by tail number) and clearly distinguishes its role from siblings by positioning itself as 'the first step in any value this tail workflow', separating it from value_aircraft and search_aircraft.

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?

Clearly frames usage as the entry point to a valuation/reference workflow and identifies the downstream IDs it supplies. However, it never explicitly names the alternatives (e.g. search_aircraft) or states when-not to use this tool, which would push it to a 5.

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