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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds value beyond them by disclosing the default branch behavior (all suitable categories returned when category is omitted) and the nature of the output (indicative min/max USD, not a firm quote).

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 tight sentences, front-loaded with the purpose and output format. The final sentence duplicates the aircraftCategory schema description ('When omitted, estimates for all suitable categories are returned'), which is the only wasted clause.

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 no output schema, the description correctly carries the return-value burden by naming the min/max USD range. Combined with 100% schema coverage and full annotation safety hints, an agent has what it needs; only the sibling-routing question remains unaddressed.

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%, so all four parameters are already documented, including the enum values and the 'used to filter suitable aircraft' note on passengers. The description only echoes the aircraftCategory omission behavior already stated in the schema, adding no new syntax or format guidance.

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 and resource (returns a price estimate for a private charter flight) plus the exact return shape (min/max USD range between two locations). The purpose is unmistakable, though it does not explicitly contrast itself with siblings like get_flight or search_empty_legs.

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 explains the optional aircraftCategory filter and what happens when it is omitted, which is useful context for calling it. However, it never says when to reach for this tool instead of get_flight, request_booking, or search_empty_legs, leaving the routing decision to inference.

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