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

The description adds behavioral context beyond the readOnlyHint annotation: prices are 'cached fares in AUD' from a specific site, 'refreshed regularly and indicative, not live availability', and it instructs the agent to 'Always present the travel dates alongside prices'. These are non-obvious behavioral traits that the agent must know, and they do not contradict annotations.

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 concise: three meaningful sentences that front-load the core purpose, then add critical behavioral notes (pricing source, instruction to present dates), and end with usage guidance. No fluff or redundancy.

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 query tool with an output schema (return values covered there) and annotations already confirming safety, the description covers all essential operational context: scope (known origin/destination), pricing source and currency, necessity to present dates, and when to use an alternative. Nothing critical 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 does not add parameter-specific semantics beyond what the schema already explains (e.g., origin codes, date window). It mentions the general purpose but does not enrich individual parameter meanings, so no credit beyond baseline is warranted.

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 clearly states the verb 'get' and the resource 'cheapest fare for each departure date in a date window', with explicit constraints ('For a known origin and destination'). It differentiates from the sibling tool search_deals by naming it directly, making the tool's function unambiguous.

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 provides an explicit usage rule: 'Use this for "cheapest flights from Sydney to Bali in September" queries; use search_deals for curated editorial deals.' This directly instructs when to choose this tool over an alternative, leaving no room for inference.

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