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 adds genuinely useful behavioral context: the result is a probability estimate ('Expected', 'probability of Starlink or another system, or none') derived from the aircraft type typically assigned, not a live Wi-Fi status. That heuristic nature is important for interpreting the answer.

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 front-loaded sentences: purpose first, then Args with parameter formats. No filler, though the inline 'Args:' enumeration is slightly terse/telegraphic rather than fully integrated prose.

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?

An output schema exists, so return values need not be explained, and the annotations cover the safety profile. For a two-parameter read-only lookup, purpose, semantics, and the probabilistic nature of the result are all covered; only sibling differentiation 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 0%, so the description must carry the load, and it does: it documents both parameters, including the IATA format with an example ('UA1') and the date format ('optional YYYY-MM-DD'). It does not say what happens when date is omitted (default/today) or which flight instance the date selects, leaving a small gap.

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 ('Expected in-flight Wi-Fi for a flight') and scopes it to the aircraft usually flying the route. It is clear what the tool returns, but it never distinguishes itself from the sibling airline_wifi, which an agent could easily confuse with this flight-level tool.

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: you supply a flight number to get Wi-Fi expectations for that flight. There is no explicit when-to-use, when-not-to-use, or pointer to airline_wifi as the airline-level alternative, which is the most likely selection ambiguity for this agent.

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