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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds real context: pricing is indicative and excludes the exclusions named (positioning, landing, handling), rates mirror the public altivojets.com calculator, and currency follows the departure market. It does not cover auth, rate limits, or latency, so it is not a 5.

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 pricing scope before the output inventory and the estimate-vs-quote caveat. Dense but nearly every clause carries information; the enumeration of outputs is long but necessary in the absence of an 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?

With no output schema, the description carries the return-shape burden and discharges it fully by listing every return field, plus the estimate/quote caveat. For a read-only 7-param tool with full schema coverage, nothing an agent needs to invoke it correctly is missing.

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 the baseline is 3, but the description adds meaning the schema does not: the default currency is the local currency of the departure market unless the currency param overrides it, and the price is driven by aircraft size and one-way vs. return. These map to aircraft_category, return_date, and currency beyond the schema's own wording.

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 ('indicative full-charter price') and enumerates the exact outputs: price range before taxes, estimated taxes, all-in range, flight time, fuel stops, recommended size. This clearly separates it from siblings like request_quote and find_operators, which an agent can distinguish without opening a schema.

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 closing sentence gives explicit positioning: 'An estimate, not a quote: the operator's quote confirms positioning, landing and handling.' This tells the agent when this tool is the right choice versus a firm quote. It stops short of naming the request_quote sibling directly, so the routing is clear but not fully explicit.

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