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

With no annotations, the description carries the full behavioral burden. It does add useful non-schema detail: the request costs 20 credits and returns dates, airports, times, and aircraft. It omits authority/API-key requirements, rate limits, empty-result behavior, and any note on whether legs are deduplicated or how far back coverage extends.

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?

A single front-loaded sentence with the purpose first, then format examples, then return fields, then cost. No filler sentences and nothing redundant.

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 three-parameter lookup with no annotations and no output schema, the definition covers what the tool returns and what it costs, which is the essential part. It is still incomplete because the two optional parameters that shape the result set are unexplained and behavioral context (auth, limits, empty results) is absent.

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 define callsign, days, and limit. It only illustrates the callsign format; the days lookback window (1–3650, default 30) and the result limit (1–100, default 20) are never explained, leaving two of three parameters with no semantics anywhere.

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 resource and scope: historical legs ('as flown') for a flight number/callsign, with concrete format examples (UAL1, BAW117) and the data returned. It implicitly separates itself from live-status siblings via 'past' and 'as flown', but never names an alternative to make the distinction explicit.

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: an agent can infer this is the historical lookup keyed by callsign, versus live/reliability/board siblings. There is no explicit when-to-use, when-not, or 'use X instead' guidance, and nothing says what happens when no past legs exist.

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