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

Annotations only declare read-only/idempotent/non-destructive; the description adds genuinely new behavior information: it performs no action itself, it emits step-by-step screens/buttons/fields, and the actual work is delegated to the browser tools. It also explains why there is no API path (Airalo's API is partner-only), which pre-empts an agent looking for an API alternative. It stops short of describing the exact return shape.

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 core behavior is front-loaded in the first two sentences, but the closing sentence about Airalo's partner-only API is tangential justification rather than operational guidance, and the mix of 'list my eSIMs' with 'returns step-by-step instructions' makes the paragraph feel internally inconsistent rather than tight.

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 parameters and no output schema, the description must carry the full burden of explaining what comes back, and it does so only at a high level ('screens, buttons, fields'). The critical ambiguity of whether eSIM data is returned or only instructions is left unresolved, which is the main thing an agent needs to know before calling.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline applies.

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 names the resource (the user's own eSIMs in their Airalo account) but then says the tool 'Returns how to do it in Airalo step by step (screens, buttons, fields) and opens nothing by itself.' That reframes it from a data-listing tool into a guide-producing tool, which contradicts the name/title 'List my eSIMs' enough that an agent cannot tell whether it will receive eSIM data or instructions.

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 does say what to do next ('then do it with the cotlet_browser_* tools in the user's Airalo Cloud Browser'), which gives implied usage context. But it never states when to prefer this over directly navigating with the browser tools, and 'cotlet_browser_*' is a wildcard rather than named siblings.

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