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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds substantive behavior beyond that: the result is fare-per-date rather than flight listings, and roundtrip also returns the return leg. It omits any range limits, caching/pricing freshness, or pagination behavior, so it is strong but not exhaustive.

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-loads what the tool returns, then formats, then routing to search_flights. The trailing sentence about the card placement is longer than needed and partly decorative, but it does encode real routing context rather than padding.

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?

An output schema exists, so return-value documentation is not required, and the description covers purpose, formats, trip types and the sibling alternative. What's missing is operational context such as any maximum range length or fare-freshness caveats, which matter for a date-range calendar query.

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 parameters are already documented, and the schema itself supplies the IATA examples (DEL, DXB) and YYYY-MM-DD format. The description restates those conventions rather than adding new semantics (e.g. whether cabin affects which cheapest fare is returned, or how trip_type pairs with start/end dates). 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?

States a specific verb and resource ('shows a Paytm fare calendar: the cheapest flight fare for every date in a range') and explicitly disambiguates from the closest sibling by saying it 'lists no individual flights; requests to show or find flights are served by search_flights.' An agent can route correctly without opening either 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 explicit when-to-use ('spot the cheapest days to fly', cheapest *dates/days*) and when-not ('requests to show or find flights are served by search_flights'), plus the alternative. It even explains the intended UI relationship to the search_flights card, which tells the agent when a calendar result is expected.

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