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

Annotations already cover readOnly, idempotent, and non-destructive hints. The description adds the behavioral nuance that this returns the scheduled timetable even if the flight's live status differs (delays, cancellations), which is beyond what annotations provide. But it does not disclose error handling, rate limits, or what happens when no schedule exists. It adds some context but not rich detail.

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 two sentences: the first states the purpose with essential qualifiers, the second gives a concrete example. It is front-loaded with the core purpose and contains no filler. The example is instructive without being verbose. Excellent efficiency.

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?

For a read-only lookup tool with 6 fully documented required parameters and no output schema, the description adequately conveys what is returned (departure/arrival airports and times) and the key qualifier about operational status. It does not detail the exact response structure, but since there is no output schema, the description gives enough for an agent to know what to expect. Minor gap: no mention of failure modes or default behavior, but overall sufficient.

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 every parameter already has a clear definition. The description includes an example call with concrete values, which reinforces usage but does not add new semantic meaning beyond the schema. It does not clarify any parameter nuances not already in the schema, so baseline 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 description clearly states the tool returns the published scheduled timetable (departure/arrival airports and times) for a carrier+flight number on a date. It explicitly distinguishes this from live operational status by saying 'regardless of live operational status', which differentiates it from sibling tools like flightstats_flight_status without naming them. The verb is implicit but the resource and scope are unambiguous.

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 description implies when to use this tool via 'regardless of live operational status' – suggesting this is for static schedules, not real-time tracking. However, it does not explicitly name alternatives (e.g., flightstats_flight_status) or state when not to use this tool. The guidance is only implied, not explicit, so it falls short of a 4.

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