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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), yet the description adds substantial behavioral context beyond them: it explicitly disclaims what it will NOT do ('never estimates an inspection due date or airframe hours: those are not in the data') and characterizes each signal's structure and epistemic status (kind, severity, underlying facts; hints rather than facts). This is exactly the honesty about limitations that annotations cannot carry.

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?

Three sentences, front-loaded with the composition of signals, then limitations, then framing. The middle enumeration is dense but each clause maps to a real signal; the closing caveat earns its place. Minor verbosity from the parenthetical domain references, but no filler.

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 an output schema present, return-value detail is unnecessary, and the description still covers signal composition, structure, and the critical data-limitation caveats. For a single-parameter, read-only analysis tool, an agent has everything needed to invoke it and interpret results 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?

There is a single parameter with 100% schema description coverage, including the Brazilian format example and length bounds, so the schema already carries the parameter semantics. The description adds nothing about the registration argument, leaving the baseline 3 appropriate.

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 precise verb+resource ('Composes what is known about one registration into maintenance signals') and enumerates the concrete signals produced (CVA/CA validity, RBAC 145 shop stays, idle days, utilization trends, coverage/owner status), so the agent knows exactly what comes back. It is clearly distinct from siblings like jt_aircraft_base or jt_aircraft_history by domain, though it never names an alternative explicitly.

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?

It frames the output's intended use ('hints to prioritise outreach, not facts about the aircraft'), which implies when the tool is useful. However, it does not state when to prefer it over siblings such as jt_aircraft_history or jt_aircraft_base, nor any exclusions, so the routing guidance is only implied.

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