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

Annotations already establish read-only, idempotent, open-world, and non-destructive behavior. The description adds meaningful behavioral context beyond that: only verified public retail offers are ranked, unverified prices remain unknown, rankings apply only to verified exact matches in pricePosition, and alternatives are separately labeled.

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 compact and front-loaded: it starts with the comparison action and scope, then explains outputs and verification limitations. Every sentence contributes useful information without repetition.

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 relatively complex 9-parameter comparison tool with no output schema, the description does well on return content and verification caveats. However, it leaves several parameters and usage alternatives unexplained, so it is only partially complete for correct invocation.

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 very low at 11%, so the description carries a heavy burden. It mentions country, trip duration, data preference, and currency, but omits meaningful explanation for providers, quantity, locale, unlimited, and includeTechnicalDetails.

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 states a specific verb and resource: compare verified public retail travel eSIM offers, scoped by country, trip duration, data preference, and currency. It is clear enough to distinguish this from plan-listing or retrieval siblings, but it does not explicitly name those alternatives.

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 implies when to use the tool by describing the comparison inputs, but it gives no explicit when-not guidance or named alternatives such as get_esim_plan or search_esim_destinations. The caveat about verified exact matches helps, but routing guidance remains implicit.

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