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

Annotations already cover safety (readOnly, idempotent, openWorld, non-destructive), so the bar is lower. The description adds that fares are 'recent' (freshness hint) and references an undocumented 'say' output field, which is genuinely useful since no output schema exists — but it never explains what 'say' contains or how results are shaped.

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?

Short and front-loaded, but the opening 'Fare Deals.' merely restates the tool name and earns nothing, and the closing 'The say field is a ready-made answer' is cryptic rather than informative.

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 read-only search tool with a fully documented schema, the core is adequate. However, with no output schema, the description should explain the 'say' field it advertises, and it offers no routing against its faredeals siblings.

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 all nine parameters are already documented in the schema with examples. The description adds no parameter meaning beyond that, which is the baseline 3 when the schema does the heavy lifting.

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: cheapest recent fares from a city to a place or anywhere. That is clear enough to distinguish the tool's function, but it does nothing to separate it from the sibling faredeals_cheapest_dates, which plausibly overlaps.

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?

There is no when-to-use guidance, no conditions, and no mention of the sibling tools faredeals_cheapest_dates or faredeals_look_up_place. The agent must infer routing entirely on its own.

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