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

Annotations already declare the full safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description goes beyond them by disclosing the business rules that determine eligibility — profile not installed and inside the refund window — which is genuine behavioral context an agent could not infer from the 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?

One tight sentence with the verb and result front-loaded and the qualifying conditions appended after a colon. No filler, no repetition of the title.

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 parameterless, read-only list tool with no output schema, the description covers what is returned and the exact qualifying conditions, which is the essential information. It could optionally note the return shape or ordering, 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?

The tool takes no parameters, so the baseline is 4. The description adds no parameter meaning because there is none to add, and schema coverage is 100% regardless.

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 (Returns) and a precisely scoped resource (first-eSIM wallet top-ups refundable to the card), which inherently separates it from list_wallet_activity. It does not, however, name or contrast against any sibling, so it stops short of the top mark.

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 eligibility criteria ('profile has not been installed', 'inside the refund window') imply when the tool is relevant, giving a competent agent enough to act. But there is no explicit when-to-use statement, no exclusions, and no routing to alternatives such as list_wallet_activity.

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