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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds genuinely non-structured context: prices are observations that can change or sell out, and the agent should tell users to confirm before booking. It omits pagination behavior, but that is minor for a bounded list tool.

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 scope, then the sibling routing rule, then return fields. The long enumeration of returned fields is justified given there is no output schema, though it makes the description dense; every clause still carries information.

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 supplies the return-field inventory (origin, destination_airport, price/currency, google_price_signal and related fields), the freshness caveat, and the sibling alternative. An agent has everything needed to invoke and interpret results correctly.

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 all three parameters (limit, nights, origin) are already fully documented, including omit-to-search-all behavior. The description's mention of "one departure airport or across all tracked US airports" only restates the schema, adding no new syntax or constraints; baseline 3 applies.

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 (list) and resource (cheapest round-trip economy fares), with scope spelled out: from one departure airport or across all tracked US airports. It names the sibling get_todays_deals and the condition distinguishing it, so an agent can pick 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 concrete trigger examples ("cheap flights from SFO", "where can I fly for under $500") plus an explicit routing rule: for deals re-verified today, use get_todays_deals. Both when-to-use and the alternative are stated, not inferred.

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