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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and external-lookup behavior are covered on the structured side. The description adds the device categories and example model strings but says nothing about return content, confidence, or how unsupported/unknown models are reported.

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?

A single front-loaded sentence: the verb and resource come first, followed by the scope categories and illustrative examples. No wasted words.

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 one-parameter, read-only lookup with no output schema, the definition is nearly sufficient: purpose, scope, and input format are all clear. The remaining gap is that it does not suggest what a result looks like or how to interpret an unknown model, which slightly matters for an open-world lookup.

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 the only parameter is simply documented as 'Device model name.' The description goes beyond that by giving realistic model-string formats ("iPhone 15 Pro", "Galaxy S23", "Pixel 8"), which meaningfully guides how to populate the field.

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 (Checks) and resource (eSIM support for a device model), and lists the device categories it covers (phone/tablet/watch) with concrete model examples. It is unmistakably distinct from the sibling tools, which deal with flights, destinations, countries, and plans.

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?

Usage is implied by the narrow purpose: an agent would infer it is for verifying eSIM capability of a known model. There is no explicit when-to-use/when-not guidance, no note about what to do for ambiguous or unknown models, and no named alternatives.

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