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

Goes well beyond the read-only/idempotent annotations: enumerates the verdict vocabulary, lists the returned fields (expected times, reasons, cancellation chance, post-departure lateness and landing), and instructs the agent to surface the willmyflightbedelayed.com link because that page updates over time. That last point is genuine behavioral context an agent could not derive from structured fields.

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?

Three front-loaded sentences with no filler; the output contents are stated before the advisory about the link. Slightly dense in the first sentence but each clause carries information.

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-value burden and does so fully: verdict scale, timing fields, reasons, cancellation chance, and post-departure state. Nothing an agent needs to call it or relay results 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 coverage is 100%, so both parameters are already documented. The description only adds a forecast-horizon nuance ('today or tomorrow'), which actually sits slightly in tension with the schema permitting arbitrary YYYY-MM-DD dates, so it adds little and could mildly confuse.

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 verb: a delay/cancellation forecast for ONE flight number, today or tomorrow. The explicit 'one flight number' scope distinguishes it from route-level siblings like flights_between and carrier-level ones like airline_status without needing to name them.

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?

Gives clear context for when the data applies (today or tomorrow, and that it becomes retrospective after departure). It does not explicitly name the alternatives or say when NOT to use it, so an agent must infer routing from scope alone.

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