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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses substantial behavior not visible in structured data: automatic codeshare resolution with the marketing_flight/operating_flight distinction and the instruction to track the OPERATING flight, tolerant input normalization with concrete examples, and the array return shape with cardinality behavior ('usually 1 when direction is set'). No contradiction with the annotations exists; 'resolve' is consistent with readOnlyHint=true.

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?

The description is dense — roughly five distinct pieces of information across four sentences — but every sentence earns its place: purpose, codeshare behavior, usage routing, input tolerance, return shape. It is front-loaded with the core function before edge-case behaviors, though the codeshare segment could arguably be trimmed for brevity.

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 present, the description correctly takes on the burden of explaining the return value: array of matching operations, the codeshare:true shape, and the operating_flight field. It also covers date/direction semantics relevant for correct pickups and dropoffs. For a read-only resolver with three well-documented params, nothing an agent needs to call 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 description coverage is 100%, so the schema already documents flight_number format tolerance, the YYYY-MM-DD date requirement with its dd/mm/yyyy warning, and the direction enum/default. The description adds contextual rationale (pickup/dropoff semantics for date and direction) but does not reveal anything about the parameters themselves beyond what the schema provides, so the baseline of 3 is 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 first sentence names a specific verb and resource ('Resolve a flight number') and lists the concrete outputs (airports, terminals, scheduled times, status). It clearly differentiates from sibling resolvers like resolve_train and resolve_location while sharing the resolve_* naming pattern.

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?

Explicitly states when to invoke it: 'Use BEFORE book_ride whenever the customer provides a flight number', naming the downstream sibling and the motivating reason (correct pickup time and terminal). The airline/airport domain context is unambiguous, leaving no ambiguity about when this prevents errors.

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