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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds substantive behavior the annotations do not: the payload fields returned (airports, scheduled vs expected times, terminal, gate, baggage belt, in-air flag, last reported position) and the live-tracking/alert side effect. Minor gap: no mention of behavior for an unknown or ambiguous flight number.

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 first sentence is a long undifferentiated list of returned fields, and the closing clause about a slashtel.com link and free email alerts reads as promotion rather than information an agent needs to select or invoke the tool. The usage sentence is front-loaded well, but roughly a third of the text does not earn its place.

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 does so well by enumerating the key fields. For a two-parameter read tool with full annotation coverage, that is nearly complete; only error/not-found behavior is unstated.

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 both parameters are already fully documented including the enum and the departure-airport-local-time nuance. The description only restates the yesterday/today/tomorrow window and adds no format or disambiguation guidance beyond the schema; baseline 3 applies.

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 names a specific verb and resource ("Live status of a flight by its number") and bounds the scope to yesterday/today/tomorrow, so an agent knows exactly what it retrieves. It does not differentiate from sibling tools, though the siblings (eSIM, top-up, price alerts) are not real alternatives here, so the cost of that omission is low.

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?

"Use it when someone asks where a flight is, whether it is delayed, or when it lands" gives concrete triggering intents, which is more than most definitions do. There is no explicit when-not guidance (e.g. historical flights, multi-leg itineraries), but the day enum implicitly bounds usage.

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