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

Beyond the annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false), the description discloses rich behavioral details: it returns a verdict and claim link, performs AeroDataBox lookups for past flights, handles optional status/delay/arrival fields, flags airport mismatches, defines compensation eligibility (3+ hour delays or cancellations), and requires authentication.

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 a single dense paragraph with no wasted words; it front-loads the core purpose and then layers necessary operational details. It could be slightly more structured for readability, but every sentence earns 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?

For a 12-parameter write tool with no output schema and open-world lookups, the description covers all essential aspects: the mutation side effect, the returned verdict/amount/link, fallback lookup behavior, compensation rules, and authentication. Nothing critical for correct invocation 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 description coverage is 100%, so the baseline is 3; the description adds extra meaning by clarifying that the optional status, delay, and actual arrival fields are all looked up when omitted (the schema only mentions lookup for status). It also reinforces IATA code formats, though most parameter details are already in the schema.

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 states a specific verb ('Adds') and resource ('a flight to the person's Untap account'), plus the outcome ('returns the UK261 or EU261 verdict, the amount and the airline's claim link'). It clearly distinguishes itself from siblings like add_train_journey and check_flight_compensation by combining an add operation with an immediate eligibility verdict.

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 usage through the verb and resource, and gives some context (e.g., 'For past flights Untap checks AeroDataBox flight-status records') plus a prerequisite ('Requires sign-in to Untap'). However, it never explicitly states when to choose this tool over alternatives such as check_flight_compensation, nor does it name any alternatives or exclusions.

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