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

Goes well beyond the readOnly/idempotent annotations: no sign-in required, nothing saved to an account, an anonymous record retained for a year, flight-status history limited to roughly the last year, and reconciliation behavior when supplied airports disagree with the record. These are exactly the operational traits an agent needs before calling.

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?

Front-loaded with purpose and inputs, then the return payload. The long enumeration of returned fields is justified because there is no output schema, though it makes the description denser than strictly necessary.

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 thoroughly: matched route, arrival delay, distance band, per-passenger amount, extraordinary-circumstances caveat, airline claim page, dispute body, deadline guidance, and claim pack. Privacy/retention and mismatch handling complete the picture.

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 the schema already documents every parameter (baseline 3). The description adds genuine meaning beyond it by explaining data-source selection: what_happened/arrival_delay_minutes are used when given, otherwise the flight-status record is consulted, and it reiterates that price_paid feeds account-saving rather than the amount.

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 and resource ('Works out compensation for a delayed or cancelled flight'), names the governing regimes (UK261/EU261), and scopes it to flights, which separates it from siblings like check_train_delay or scan_for_claims. An agent can identify what this tool produces without opening the schema.

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: it takes a flight number and date, and explains that the incident is either looked up in flight-status records or supplied via what_happened/arrival_delay_minutes. It does not name or exclude alternatives (e.g. save_claim, get_claim_instructions), so selection guidance is contextual rather than explicit.

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