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

Annotations already declare this a read-only, idempotent, non-destructive, closed-world operation, so the safety profile is covered. The description adds genuinely new context by enumerating the kinds of content returned (local currency, popular apps, caveats, guide link) and the list-all fallback behavior, which the annotations do not convey.

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?

One sentence plus a short clause, with the core purpose front-loaded and the omit-country rule appended where it is relevant. No redundant restatement of the title or schema.

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 compensates by previewing the returned content categories and the list-all mode, which is enough for an agent to call it correctly. It stops short of describing result shape or localization interactions between lang and country, but 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% and the lang default and enum are documented there, so the schema carries the parameter burden. The description adds the meaningful behavior for omitting country (returns all guides), but says nothing extra about lang or accepted country-name formats beyond what the schema already states.

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 (card payment tips per country, including currency, apps, caveats, and a guide link) with a clear scope, which is more than the title alone conveys. It does not, however, distinguish itself from siblings like get_foreign_card_terms or how_to_pay_from_russia, leaving overlap for the agent to resolve.

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?

"Omit country to list all guides" gives one concrete usage rule for the no-argument case. There is no guidance on when to pick this tool over the closely related siblings (get_foreign_card_terms, how_to_pay_from_russia), so selection remains implied rather than stated.

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