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

Annotations already declare this a read-only, idempotent, non-destructive, closed-world fetch, so the safety profile is covered. The description adds genuinely useful context beyond that: it discloses which spec fields come back only 'where the listing gives them' (i.e., partial data is possible), that the seller is never named, and that the desk confirms specs with the seller's broker — though it says nothing about error behavior for an invalid reference.

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?

Two sentences, front-loaded with the resource and followed by the disclosure caveat about the seller. The long parenthetical spec enumeration is dense but earns its place by previewing the payload given there is no output schema.

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 one-parameter, read-only tool with full schema coverage and no output schema, this is complete: it describes the returned contents field-by-field and flags the two things an agent could otherwise get wrong — missing specs and the anonymity of the seller.

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% and the single parameter is documented with a concrete format example and the alternative page-address form, so the schema carries the load. The description's phrase 'by its reference' restates rather than extends that meaning, which is the baseline 3 case.

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 names a specific verb+resource: it returns one aircraft-for-sale listing by reference, and enumerates what the payload contains (engines and times, APU, airframe cycles, avionics, maintenance, interior/exterior, page link). That clearly separates it from list_aircraft and search_aircraft_for_sale, though neither sibling is named explicitly, keeping 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?

Usage is only implied: 'by its reference' signals this is the detail fetch that follows a search, and the schema's example reference 'from search_aircraft_for_sale' reinforces that, but the description itself gives no explicit when-to-use or when-not-to-use guidance versus search_aircraft_for_sale or list_aircraft.

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