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

Annotations already state readOnlyHint and non-destructive, so safety is covered. The description adds that it matches app behavior, implying real-world data, and mentions availability and credits per country. This provides useful context beyond 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 two sentences, front-loaded with the main purpose, and every word earns its place. It efficiently conveys the prerequisite and key details.

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 single-parameter read-only tool with a rich output schema, the description covers the prerequisite, the semantics of serviceCode, and the conceptual match to the mobile app. 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 coverage is 100%, but the description reinforces that serviceCode is the short code from the summary field, giving concrete examples (tg, wa, fb). This adds practical guidance beyond the schema's basic description.

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 loads countries for a service, requires a serviceCode from the summary, and matches app behavior. It distinguishes itself from legacy /prices APIs and other SMS tools.

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 tells the agent to use it after obtaining serviceCode from summary, which is clear context. However, it doesn't explicitly say when not to use it vs. sibling tools like ucode_sms_countries, though it does steer away from legacy APIs.

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