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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds non-obvious traits: it runs multi-city optimization, computes a fairness score, and requires locale inference with specific language mapping, plus currency defaults. This goes beyond annotations, though it omits output format details.

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 front-loads the core purpose, but includes three multilingual example queries that elongate it. It also repeats the title and some schema content, making it slightly less lean than ideal. Still, the structure is logical.

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?

The tool has 8 parameters and no output schema, so the description needs to explain behavior and return values. It covers usage and locale, but doesn't describe what the agent should do with the response (e.g., present a destination, show map, etc.). This is a notable gap given no output schema.

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% and clearly documents all parameters including locale instructions and currency defaults. The description largely repeats this info (e.g., locale inference, currency mappings) without adding new parameter semantics beyond the schema. Hence baseline 3.

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 tool finds the cheapest and fairest common destination for 2-5 people from different cities, with concrete example queries. This specific verb+resource scope distinguishes it from sibling tools like search_flights or cheapest_dates.

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?

It explicitly says 'Use when the user asks to coordinate a trip across multiple origins and needs a shared destination,' providing a clear usage context. However, it doesn't name alternatives or explicitly state when not to use, so it stops short of full when/when-not guidance.

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